turbosystem - بیت دانلودs2.bitdownload.ir/engineering/all.ansys/ansys 12... · 2019. 5....

TurboSystem

Release 12.0ANSYS, Inc.April 2009Southpointe

275 Technology Drive ANSYS, Inc. iscertified to ISO9001:2008.

Canonsburg, PA [email protected]://www.ansys.com(T) 724-746-3304(F) 724-514-9494

Copyright and Trademark Information

© 2009 SAS IP, Inc. All rights reserved. Unauthorized use, distribution or duplication is prohibited.

ANSYS, ANSYS Workbench, Ansoft, AUTODYN, EKM, Engineering Knowledge Manager, CFX, FLUENT, HFSS and any andall ANSYS, Inc. brand, product, service and feature names, logos and slogans are registered trademarks or trademarksof ANSYS, Inc. or its subsidiaries in the United States or other countries. ICEM CFD is a trademark used by ANSYS, Inc.under license. CFX is a trademark of Sony Corporation in Japan. All other brand, product, service and feature namesor trademarks are the property of their respective owners.

Disclaimer Notice

THIS ANSYS SOFTWARE PRODUCT AND PROGRAM DOCUMENTATION INCLUDE TRADE SECRETS AND ARE CONFIDENTIALAND PROPRIETARY PRODUCTS OF ANSYS, INC., ITS SUBSIDIARIES, OR LICENSORS. The software products and document-ation are furnished by ANSYS, Inc., its subsidiaries, or affiliates under a software license agreement that contains pro-visions concerning non-disclosure, copying, length and nature of use, compliance with exporting laws, warranties,disclaimers, limitations of liability, and remedies, and other provisions. The software products and documentation maybe used, disclosed, transferred, or copied only in accordance with the terms and conditions of that software licenseagreement.

ANSYS, Inc. is certified to ISO 9001:2008.

U.S. Government Rights

For U.S. Government users, except as specifically granted by the ANSYS, Inc. software license agreement, the use, du-plication, or disclosure by the United States Government is subject to restrictions stated in the ANSYS, Inc. softwarelicense agreement and FAR 12.212 (for non-DOD licenses).

Third-Party Software

See the legal information in the product help files for the complete Legal Notice for ANSYS proprietary software andthird-party software. If you are unable to access the Legal Notice, please contact ANSYS, Inc.

Published in the U.S.A.

Table of Contents

Introduction to TurboSystem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1TurboSystem Workflows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Geometry Sources .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Mesh Sources .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Solution Sources .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3Examples of TurboSystem Workflows .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4Usage Notes for Specific Workflows .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Tips on using ANSYS Workbench .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5Using BladeGen .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Changing the Active Document in BladeGen .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Using BladeEditor ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Loading versus Importing a BladeGen Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Restarting a BladeEditor Session .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Modifying Spline Curves .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Adding a Hub Fillet to an Imported BladeGen Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7Creating a Full 360-Degree Fluid Zone for an Impeller ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Using ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8Using ANSYS CFX .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Connecting from a Turbo Mesh Cell .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9Changing the Geometry .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Quick Pump Tutorial ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9ANSYS BladeGen . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13ANSYS BladeEditor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

The BladeEditor User Interface .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Tree View and Details View .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19Contour Sketch Management .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20BladeEditor Toolbars ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

Feature Creation Toolbar .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21Active Selection Toolbar .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Display Control Toolbar .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

Angle and Thickness Views .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Angle View .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Thickness View .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25

User Preferences and Properties ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Blade Editing Features .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

Flow Path Contour Creation .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27FlowPath Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

Flow Cut .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29Camberline/Thickness Definition Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Importing and Exporting Angle Definition Data .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32Importing and Exporting Thickness Definition Data .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Converting Curves to Bezier or Spline .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Converting Angle Definition Data .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Forcing Interpolation of the Definition Data .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Blade Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34Splitter Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Cloned Splitter ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Independent Splitter ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Stage Fluid Zone Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Throat Area Feature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

iiiRelease 12.0 - © 2009 SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information

of ANSYS, Inc. and its subsidiaries and affiliates.

Importing Blades from ANSYS BladeGen .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Loading and Modifying Blades from ANSYS BladeGen .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45Using and Exporting Blades .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45

Export to Vista TF (.geo) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46Export as Meanline Data (.rtzt file) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47Export to ANSYS TurboGrid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

Configuring the BladeModeler License .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50ANSYS TurboGrid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53ANSYS CFX-Pre . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57ANSYS CFD-Post . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59Vista TF . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61

Vista TF User's Guide .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61Vista TF Setup Cell Properties ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62Customizing the Vista TF Template Files ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66Vista TF Context Menu Commands .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67

Vista TF Reference Guide .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Running Vista TF from the Command Line .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68Input and Output Data Files for Vista TF .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69

The Auxiliary File with the Default Name: vista_tf.fil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69Overview of Input Files ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70Overview of Output Files ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72Specification of the Control Data File (*.con) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74Specification of the Geometry Data File (*.geo) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83Specification of Aerodynamic Data File (*.aer) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91Specification of Correlations Data File (*.cor) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101Specification of the Output Data File (*.out) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111Specification of the Text Data Files (*.txt) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114Specification of the CFD-Post Output Files (*.csv) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116Specification of Convergence History Data File (*.hst) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117

Software Limitations .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118Streamline Curvature Throughflow Theory .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118

The Equations .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119The Mean Stream Surface .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119The Grid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120Ductflow and Throughflow .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121Iterative Solution Procedure .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121Initial Estimate .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122Radial Equilibrium Equation .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122Combination of Velocity Gradient and Continuity Equations .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122Relaxation Factors ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123Streamline curvature .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123Equations for Enthalpy and Angular Momentum ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123Boundary Conditions .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123Empirical Data .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124Blade-to-blade Solution .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124Spanwise Mixing .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124Streamline Curvature Throughflow Theory: Bibliography .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125

Appendices .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126Appendix A: A Note on Sign Convention for Angles and Velocities ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

Definition of Blade Lean Angles .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128Definition of Meridional Streamline Inclination Angle or Pitch Angle .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129Definition of Blade Angle .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129

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TurboSystem

Appendix B: Example of a Control Data File (*.con) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130Appendix C: Example of a Geometry Data File (*.geo) for a Radial Impeller ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130Appendix D: Example of an Aerodynamic Data File (*.aer) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132Appendix E: Examples of Correlations Data Files (*.cor) ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133Appendix F: Troubleshooting .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138

Input-output Errors ... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139Convergence .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140Reverse Flow .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142Choking .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142Computational Grid .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144Other Numerical Issues .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145

Appendix G: The RTZTtoGEO Program ..... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147Index .... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151

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TurboSystem

Introduction to TurboSystem

TurboSystem is a set of software applications and software features for designing turbomachinery in theANSYS Workbench environment. It consists of the following components:

• ANSYS BladeGen: a geometry creation tool that is specialized for turbomachinery blades. For details,see "ANSYS BladeGen" (p. 13).

• ANSYS DesignModeler: a general purpose geometry preparation tool that is integrated in ANSYSWorkbench. This CAD-like program is primarily used to prepare CAD geometry models for analysis byother ANSYS Workbench based tools. For details, see DesignModeler Help.

• ANSYS BladeEditor: a plugin for DesignModeler for creating blade geometry. ANSYS BladeEditor providesthe geometry link between BladeGen and DesignModeler, and therefore links BladeGen with otherANSYS Workbench based applications. For details, see "ANSYS BladeEditor" (p. 19).

• ANSYS TurboGrid: a meshing tool that is specialized for CFD analyses of turbomachinery blade rows.For details, see "ANSYS TurboGrid" (p. 53).

• ANSYS CFX-Pre: a general-purpose CFD preprocessor that has a turbomachinery setup wizard for facilit-ating the setup of turbomachinery CFD simulations. For details, see "ANSYS CFX-Pre" (p. 57).

• ANSYS CFD-Post: a general-purpose CFD postprocessor that has features for facilitating the post-pro-cessing of turbomachinery CFD simulations. For details, see "ANSYS CFD-Post" (p. 59).

• Vista TF: a streamline curvature throughflow program for the analysis of turbomachinery. This programenables you to rapidly evaluate radial blade rows (pumps, compressors and turbines) at the early stagesof the design. For details, see "Vista TF" (p. 61).

For information about using TurboSystem in various workflows, see "TurboSystem Workflows" (p. 3).

1Release 12.0 - © 2009 SAS IP, Inc. All rights reserved. - Contains proprietary and confidential information


TurboSystem Workflows

TurboSystem is a set of software applications and software features that help you to perform turbomachineryanalyses in ANSYS Workbench. The software applications and features are listed in "Introduction to

TurboSystem" (p. 1). This chapter describes the primary ways of using TurboSystem.

The following topics are discussed:Geometry SourcesMesh SourcesSolution SourcesExamples of TurboSystem WorkflowsUsage Notes for Specific WorkflowsQuick Pump Tutorial

Geometry Sources

The turbomachinery geometry is typically provided by one of the following cells:

• Blade Design cell of a BladeGen system

• Geometry cell of a Geometry or Mesh system

This can be based on an upstream Blade Design cell.

If you want to pass the geometry to the Turbo Mesh cell of a TurboGrid system, you must useBladeEditor to export to ANSYS TurboGrid.

Mesh Sources

The mesh is typically provided by one of the following cells:

• Turbo Mesh cell of a TurboGrid system

• Mesh cell of a Mesh system

Solution Sources

You can use one of the following systems to compute and report performance data:

• CFX component system

Use a CFX component system to perform a CFD analysis.

• Vista TF component system

Use a Vista TF component system to perform a throughflow analysis.

• Static Structural (ANSYS) analysis system

Use a Static Structural (ANSYS) analysis system to compute stresses and strains due to fluid forces andcentrifugal forces.



Examples of TurboSystem Workflows

This section shows examples of TurboSystem workflows, represented as connected systems in the Project

Schematic view. Many other configurations are possible.

CFD analysis of a centrifugal pump:

CFD analysis of a turbine stage:

Throughflow analysis and CFD analysis of a turbine stage:



Usage Notes for Specific Workflows

This section describes TurboSystem-related workflow issues and recommended practices:Tips on using ANSYS WorkbenchUsing BladeGenUsing BladeEditorUsing ANSYS TurboGridUsing ANSYS CFX

Tips on using ANSYS Workbench

The following is a list of tips that you may find useful when working in ANSYS Workbench:

• Try right-clicking on different parts of the interface to see shortcut menus.

• You may find Compact Mode to be useful. Select View > Compact Mode from the ANSYS Workbench

menu or click to turn the Project Schematic view into a small, non-intrusive “title bar”that is always visible. To return to Full Mode, hover the mouse over the title bar, then, after the window

has expanded, click Restore Full Mode in the upper-right corner of the application window.

• Use the Files view to determine which files were created for each cell/system. It is easiest to find filesassociated with a specific cell by sorting the view by Cell ID. This will sort the list by system and thenby cell.

• When selecting a system in the toolbox, ANSYS Workbench will highlight the cells in any systems alreadyin the Project Schematic view to which a valid connection can be made.



Tips on using ANSYS Workbench

• Give unique meaningful names to all of your systems, especially if there are multiple systems of thesame type.

Using BladeGen

The following topic(s) are discussed:Changing the Active Document in BladeGen

Changing the Active Document in BladeGen

If you want to replace the active document in BladeGen, then:

1. Reset the corresponding Blade Design cell.

2. Edit the Blade Design cell or right-click it and select Import Existing Case.

Note that opening a subsequent .bgd file in the same instance of BladeGen will not replace the model as-sociated with the Blade Design cell.

Using BladeEditor

The following topic(s) are discussed:Loading versus Importing a BladeGen GeometryRestarting a BladeEditor SessionModifying Spline CurvesAdding a Hub Fillet to an Imported BladeGen GeometryCreating a Full 360-Degree Fluid Zone for an Impeller

Loading versus Importing a BladeGen Geometry

There are two basic ways of transferring a BladeGen geometry into BladeEditor

• Importing

If you import the geometry, the connection to the BladeGen geometry is maintained, and blade geometrychanges must be made by editing the upstream Blade Design cell.

• Loading

If you load the geometry, native BladeEditor features are created to represent the complete geometry,the connection to the BladeGen geometry is lost, and all geometry changes must be made by editingthe Geometry cell.

Linking from a Blade Design cell to a Geometry cell causes the BladeGen geometry to be imported intoBladeEditor. The desired import options should be set in the Blade Design cell properties. (SeeTable 1: BladeGen Blade Design Cell Properties (p. 14) for more information.) After you make the link, theGeometry cell should be updated to process the imported geometry.



Note

If you edit the Geometry cell before updating it, then the Import BGD feature details that areshown in BladeEditor may not accurately reflect the Blade Design cell properties. To refresh the

Import BGD feature properties, click in BladeEditor. It is not recommended that youedit the Import BGD properties inside BladeEditor because they will be overwritten by the prop-erties from the Blade Design cell the next time you update the Geometry cell.

For details on importing BladeGen geometries, see Importing Blades from ANSYS BladeGen (p. 41).

For details on loading BladeGen geometries, see Loading and Modifying Blades from ANSYS BladeGen (p. 45).

Restarting a BladeEditor Session

If you want to clear a BladeEditor session while maintaining the link to the upstream cell, do not use theStart Over command from the File menu in BladeEditor. Doing so would erase the incoming data from anyupstream connections — notably when there is an upstream link to a BladeGen system. Instead, return tothe Project Schematic view, right-click the Geometry cell and select Reset from the shortcut menu. Whenyou subsequently edit the Geometry cell, the upstream data is imported correctly.

Modifying Spline Curves

When a spline is initially created, it is uniquely defined by its fit points. If you move any of the points, thespline may or may not be uniquely-defined, depending on the way in which you move the points:

• If you move a fit point by using the following procedure, the resulting spline will be uniquely defined:

1. On the Sketching tab, click Spline Edit.

2. Click the spline in the viewer to select it.

3. Right-click the spline and select Drag Fit Point.

4. Drag one or more fit points to adjust the shape of the spline.

• If you move a fit point using the Drag tool on the Sketching tab, or if you change a parameter thatcontrols a fit point location, the resulting spline will not be uniquely defined. Such a spline is usable,but if you want the spline to be uniquely defined by the position of the fit points, then:

1. On the Sketching tab, click Spline Edit.

2. Click the spline in the viewer to select it.

3. Right-click the spline and select Re-fit Spline.

Adding a Hub Fillet to an Imported BladeGen Geometry

Assuming that you have already created the hub when you initially imported the BladeGen model, you canadd a hub fillet using the following procedure:

1. Edit the Geometry cell.

2. In BladeEditor/DesignModeler, in the feature tree, right-click the first feature that is listed below boththe hub and blade features, then select Insert > Fixed Radius from the shortcut menu.

This inserts a new Blend feature immediately above the feature that you right-click in the tree.



Using BladeEditor

3. Select an edge along the intersection of a blade and the hub, for each edge that is to have a fillet ofa specified size.

You may need to use viewer toolbar icons to manipulate the view beforehand. If you cannot select

an edge, confirm that the selection filter is set for selecting edges (the toolbar icon).

4. Select Extend to Limits from the toolbar.

This causes the selected edge to reach as far as possible around the blade.

5. Click Apply beside the Geometry property in the details view.

6. Set an appropriate value for the Radius property in the details view.

7.Click .

Creating a Full 360-Degree Fluid Zone for an Impeller

Assuming that you have not created the fluid zone when you initially imported the BladeGen model, youcan create a fluid zone for a full, 360° impeller model using the following procedure:

1. View the Blade Design cell properties.

To do this, right-click the Blade Design cell and select Properties from the shortcut menu.

2. In the Properties view, ensure that Create All Blades is selected.

3. Update the Geometry cell if required.

4. Edit the Geometry cell.

5. Create a Revolve feature using the master profile, and revolve it around the axis for the full 360° togenerate the annulus volume.

6. Use an Enclosure feature to subtract the solid impeller from the annulus to generate the desired full360° fluid zone.

Using ANSYS TurboGrid

The following is a list of tips that you may find useful when working with ANSYS TurboGrid:

• Session file playback in ANSYS TurboGrid in ANSYS Workbench is not supported. It is released as a betafeature. For more information about this feature, see the Beta Features section of the ANSYS TurboGridrelease notes in the online help.

• ANSYS Workbench units and appearance options are not passed to ANSYS TurboGrid.

Using ANSYS CFX

The following topic(s) are discussed:Connecting from a Turbo Mesh Cell



Changing the Geometry

Note

For more tips on using ANSYS CFX in ANSYS Workbench, please refer to the ANSYS CFX in ANSYS

Workbench chapter of the ANSYS CFX online help, which is accessible from the Help menu inCFX-Pre.

Connecting from a Turbo Mesh Cell

It is recommended that you connect the Turbo Mesh cell of a TurboGrid system to the Setup cell of a CFXcomponent system rather than to the Setup cell of a Fluid Flow (CFX) system.

Changing the Geometry

After setting up a turbomachinery simulation in a CFX component system, if you change topology or numberof blades in the mesh, then refreshing or updating the CFX Setup cell (directly or indirectly) will fail topropagate the new information correctly. This will lead to incorrect results. To compensate, you can manuallycorrect the number of blades in CFX-Pre by re-entering Turbo Mode (available from the Tools menu). Inaddition, the boundaries may need to be manually corrected in CFX-Pre.

If you generate a turbo report in CFD-Post (the latter accessed by editing the Results cell), then subsequentlymake changes that affect the upstream solution, and then update the Results cell, the resulting turbo reportwill use the updated values for any variables (such as pressure and velocity) and expressions that it uses,but the report will continue to use the old turbomachinery data (such as the number of blades and themachine axis). After updating the solution, you will have to take one of the following actions to update theturbo report:

• If you have no work that needs to be preserved with respect to the Results cell, then:

1. Reset the Results cell.

2. Edit the Results cell.

3. Load a turbo report.

• If you have done work in CFD-Post but have no work that needs to be preserved with respect to theturbo report, then:

1. Update the Results cell.

2. Reload the turbo report.

This is slower than the previously-mentioned method because the update process includes an unwantedreprocessing of the old turbo report (with new results, but old turbomachinery data). However, becausethis method does not involve resetting the Results cell, any work you have done in CFD-Post is preserved(except for any modifications you have made to the original report).

Quick Pump Tutorial

In this tutorial, you will quickly run through the steps required to simulate a water pump while usingTurboSystem.



Quick Pump Tutorial

Designing the Blade and Creating the Mesh

1. Open ANSYS Workbench and click File > Save As.

2. Save the project as QuickPump in a suitable directory.

3. In the Toolbox view, under Component Systems, double-click BladeGen.

A new BladeGen system appears in the Project Schematic view.

4. Double-click the Blade Design cell in the BladeGen system.

BladeGen appears.

5. Within BladeGen, create a new blade using Vista CPD by selecting File > New > Vista Centrifugal

Pump Design.

6. On the Geometry tab, change the number of blades from 6 to 7, then click Calculate.

The pump design is updated and the results are displayed.

7. Click Impeller Model.

8. Exit BladeGen and return to the Project Schematic view.

9. Right-click the Blade Design cell and select Create New Blade CFD Mesh.

After some time, a mesh will be created.

Note

If you receive an error message about licensing, click Tools > License Preferences and, inthe dialog box on the Geometry tab, select ANSYS BladeModeler, click Move up, thenclick OK. You should then delete the Mesh system from the Project Schematic view beforecontinuing.

10. Right click the Mesh cell of the Mesh system and select Transfer Data To New > CFX.

A CFX system is added. The additional information requirements posed by the CFX system causes the

Mesh cell to switch to an 'Update Required' state, as indicated by the symbol.

11. Right-click the Mesh cell and select Update.

12. Double-click the Setup cell in the CFX system.

CFX-Pre appears.



Setting up the Turbomachinery Simulation

You will use CFX-Pre in Turbo mode to set up physics and boundary conditions. In this case, you will specifythe same rotational rate and mass flow as specified in Vista CPD.

1. Click Tools > Turbo Mode.

2. On the Basic Settings panel, set Machine Type to Pump, Rotation Axis to Z, and leave the othersettings at their defaults.

3. Click Next.

4. On the Component Definition panel, double-click R1 and set the following values:

ValueSetting

RotatingComponent Type > Type

1450 [rev min^-1]Component Type > Value

(Selected)Wall Configuration

YesaWall Configuration > TipClearance at Shroud

aAlthough, in this case, the geometry and mesh do not model the tip clearance, specifying a tip clearance at the shroud causesthe entire shroud to be treated as being stationary (via a counter-rotating wall in the rotating frame); otherwise, the entireshroud would be treated as being a rotating wall (stationary in the rotating frame).

Leave the other settings at their defaults.

5. Click Next.

6. On the Physics Definition panel, set the following values:

ValueSetting

WaterFluid

1 [atm]Model Data > ReferencePressure

(Selected)Inflow/Outflow BoundaryTemplates > P-Total InletMass Flow Outlet

0 [atm]Inflow/Outflow BoundaryTemplates > P-Total

Per MachineInflow/Outflow BoundaryTemplates > Mass Flow

77.8 [kg s^-1]Inflow/Outflow BoundaryTemplates > Mass Flow Rate

Normal to BoundaryInflow/Outflow BoundaryTemplates > Flow Direction

High ResolutionSolver Parameters > Advec-tion Scheme

Physical TimescaleSolver Parameters > Conver-gence Control



Setting up the Turbomachinery Simulation

ValueSetting

1e-2 [s]aSolver Parameters > PhysicalTimescale

aThe time scale is approximately 1/(rotation speed [rad/s]). This gives a much more aggressive timescale than the default, forfaster convergence.

Leave the other settings at their defaults.

7. Click Next.

8. On the Interface Definition panel, verify that the periodic interface is set correctly. To do this, clickR1 to R1 Periodic 1 in the tree view and then examine the associated settings (shown in thelower portion of the panel) and highlighted regions in the viewer.

If no regions appear highlighted in the viewer, ensure that highlighting is turned on in the viewertoolbar.

9. Click Next.

10. On the Boundary Definition panel, verify that each boundary is set correctly. To do this, click aboundary listed in the tree view and then examine the associated settings and highlighted regions.

11. Click Next.

12. On the Final Operations panel, leave the operation set to Enter General Mode and click Finish.

13. Return to the Project Schematic view.

14. Right-click the Solution cell and select Update.

After some time, a CFD solution will be generated. If the progress indicator is not visible, you can display

it by clicking or, to see detailed output, right-click the Solution cell and select Display

Monitors.

15. Double-click the Results cell.

CFD-Post appears.

Viewing the Turbo Report

To see a report for the pump performance:

1. Click File > Report > Load 'Pump Impeller Report' Template.

2. Click the Report Viewer tab.

Note that if you have visited the Report Viewer tab before loading the template, or have otherwise made

any changes to the report definition after first viewing the report, you need to click in the Report

Viewer to update the report as displayed.



ANSYS BladeGen

ANSYS BladeGen is a geometry creation tool that is specialized for turbomachinery blades. BladeGen has itsown documentation that can be accessed through the user interface, or by browsing the installation directory.

The main documentation, “ANSYS BladeGen User's Guide”, is available from the Help menu in BladeGen.There, you will find general help, tutorials, and help on a series of Vista programs which run inside BladeGen:

• Vista CCD (for centrifugal compressors)

• Vista CPD (for centrifugal pumps)

• Vista RTD (for radial inflow turbines)

• Vista AFD (for axial fans)

Note

Another Vista program, Vista TF, is for throughflow analyses in turbomachinery. It has a referenceguide named "Vista TF Reference Guide" that is in this set of documentation. You can access itby clicking the following link: Vista TF Reference Guide (p. 68).

To launch BladeGen from ANSYS Workbench, add the BladeGen component system to your project schem-atic, then edit the Blade Design cell of that system.

The Blade Design cell has properties that need to be configured in order to transfer the blade geometryfrom BladeGen to BladeEditor. This transfer is represented by a link that connects a Blade Design cell to aGeometry cell.

A sample of the cell properties is shown in Figure : Properties of the BladeGen Blade Design Cell (p. 13).

Figure: Properties of the BladeGen Blade Design Cell



Table 1: BladeGen Blade Design Cell Properties (p. 14) describes each of the cell properties. These are relatedto the properties of the ImportBGD feature in BladeEditor (described at Table 3: Properties for the Import BGD

File Feature (p. 42)).

Table 1 BladeGen Blade Design Cell Properties

DescriptionNameGroup

If this property is selected, thenBladeEditor will create a HubProfile

Create Hub*Import Options

sketch for the non-flow path hub geo-metry, and will create a revolved bodyfeature called HubBody .

If this property is selected, thenBladeEditor will create all the blades

Create All Blades

using the number of blades specified inthe BladeGen model.

If this property is not selected, then onlythe first blade will be created.

If this property is not selected, thenBladeEditor will create the blade with

Merge Blade Topo-logy

four faces corresponding to the leadingedge, pressure side, trailing edge andsuction side. This can make it easier tocreate a structural mesh for the bladesin the Mechanical application.

If this property is selected, then theblade faces will be merged where theyare tangent to one another.

If this property is set to Streamwise ,then BladeEditor will loft the blade sur-

Blade Loft Direc-tion

faces in the streamwise directionthrough curves that run from hub toshroud. This is the default because thesurface is more well defined, especiallyfor flank-milled blades.

If this property is set to Spanwise ,then BladeEditor will loft the blade sur-faces in the spanwise direction throughthe blade profile curves.

This property specifies whether a shroudclearance is created. If None is selected,

Shroud Clearance

then no shroud clearance is created. Tocreate a shroud clearance, choose eitherRelative Layer or AbsoluteLayer . The blade(s) will be trimmed offat the selected BladeGen output layer,and the layer contour will be created inthe LayerProfile sketch.


ANSYS BladeGen


If Relative Layer is selected, thenthe selected Layer Number is relativeto the shroud layer, e.g., 1 implies thefirst layer closest to the shroud layer, 2implies the second closest layer to theshroud, etc.

If Absolute Layer is selected, thenthe selected layer index counts up fromthe hub layer, which is zero.

If this property is selected, thenBladeEditor will create a StageFluid-

Create Fluid Zone*

Zone body for the flow passage, andan Enclosure feature to subtract theblade body. The resulting Enclosure canbe used for a CFD analysis of the bladepassage.

If this property is selected, thenBladeEditor will create NamedSelec-

Create Named Se-lections*

tions (regions) for the typical faces ofthe blade passage, i.e., Blade , Hub,Shroud , Inflow , Outflow , Period-icA and PeriodicB . TheseNamedSelections can be used asselection groups in other ANSYS Work-bench applications, e.g., as regions inCFX-Mesh.

Note that this property is available onlyif Create Fluid Zone is selected.

This property defines the surface exten-sion length (as a percentage of the av-

Blade Extension(%)

erage hub to shroud distance) for theblade surfaces. These surfaces are exten-ded and then trimmed to the Master-Profile sketch to ensure that theblade solid correctly matches the huband shroud contours.

This property defines the surface exten-sion length (as a percentage of the av-

Periodic SurfaceExtension (%)

erage hub to shroud distance) for theperiodic surfaces. These surfaces areextended to ensure that the StageFlu-idZone is properly cut.

This property specifies the style of theperiodic interface surfaces.

Periodic SurfaceStyle

If Three Pieces is selected, then theperiodic surface is created in three con-



ANSYS BladeGen


nected pieces: one upstream of theblade, one within the passage, and onedownstream of the blade. This style canbetter accommodate highly curved ortwisted blades, and is similar to theANSYS TurboGrid style of periodic sur-face.

If One Piece is selected, then theperiodic surface is created as a singlesurface.

Note that this property is available onlyif Create Fluid Zone is set to Yes .

* These properties will only apply when you initially import the model. Any subsequent changes to theseproperties will not be propagated to downstream cells upon updating the latter.

Once the ImportBGD feature has been created (for example, by updating the Geometry cell), changing thefollowing Blade Design cell properties will have no effect:

• Create Hub

• Create Fluid Zone

• Create Named Selections

Note

In order to facilitate the use of a BladeGen model in another application (such as BladeEditor orANSYS TurboGrid), you should always ensure that the model units are set. When you create anew BladeGen model (File > New > BladeGen Model), the default units are always “Unknown”(regardless of ANSYS Workbench preferences). In this case, select Model > Properties from theBladeGen main menu and set Model Units in the Model Property Dialog.

You can access a context menu for the Blade Design cell in the BladeGen component system by right-clickingthe cell. Most of the commands that are available are standard, and are described in Systems and Cells. Thecontext menu commands that are specific to the Blade Design cell are described in Table 2: Context Menu

Commands Specific to the BladeGen Blade Design Cell (p. 16).

Table 2 Context Menu Commands Specific to the BladeGen Blade Design Cell

DescriptionCommand

This command opens BladeGen. If the cell is up todate, then BladeGen will load the associatedBladeGen model.

Edit

This command opens a file browser for selecting a.bgd file. This command is only available if the cell

Import Existing Case

is in the Edit Required state. If this command is notavailable due to having already selected a .bgd file,and you want to make the command available so


ANSYS BladeGen

DescriptionCommand

that you can select a different .bgd file, then choosethe Reset command in the context menu.

This command creates a linked Mesh system andgenerates a mesh for the associated BladeGen

Create New Blade CFD Mesh

model. This command is available only if the cell isup to date.



ANSYS BladeGen

ANSYS BladeEditor

ANSYS BladeEditor is a plugin for ANSYS DesignModeler for creating, importing, and editing blade geometry.Using BladeEditor, you can create a blade from scratch. You can also import a blade from ANSYS BladeGen.Once you have a blade in DesignModeler, you can use it as you would any geometry created in DesignModeler.In addition, you can use BladeEditor to export the geometry for use in ANSYS TurboGrid (a meshing tool)and Vista TF (a throughflow analysis tool).

The following topics are discussed:The BladeEditor User InterfaceBlade Editing FeaturesImporting Blades from ANSYS BladeGenLoading and Modifying Blades from ANSYS BladeGenUsing and Exporting BladesConfiguring the BladeModeler License

The BladeEditor User Interface

The BladeEditor user interface extends the DesignModeler user interface in the following ways:

• There are new feature types aimed at creating a blade and flow passage.

• There is a set of toolbar icons, most of which are used to create the new feature types.

• There are new views associated with some of the feature types.

• There are new context menu commands associated with the new views.

The following topics will be discussed:Tree View and Details ViewContour Sketch ManagementBladeEditor ToolbarsAngle and Thickness ViewsUser Preferences and Properties

Tree View and Details View

As with DesignModeler features, the primary user control of the new blade geometry features is throughthe tree view and details view. The tree view shows the list of the features in the current model, and providesa mechanism for you to select a feature for inserting, editing, or deleting. The tree view also shows the orderof operations in which DesignModeler will generate the model (top to bottom), and the feature dependen-cies.Figure : Tree View (p. 20) shows an example of the tree view diagram with the sketches (HubContour1 ),FlowPath (FlowPath1 ), CamThkDef (IGVCam1), and Blade (IGV) features for two blade rows.



Figure: Tree View

You might want to temporarily suppress various features to speed up the regeneration time. This can bemanaged in DesignModeler by right-clicking the feature in the tree view and selecting “Suppress”. Note thatsuppressing a feature also suppresses all dependent features below it. Sketches cannot be suppressed; theycan only be hidden or deleted.

When you click a contour sketch in the tree view, the sketch will be highlighted in the 3D viewer. When youclick on a camberline definition, the corresponding FlowPath layer contour will be highlighted in the 3Dviewer, and the angle and thickness views will be displayed for this definition. Any changes made to thesketches or camberline definitions will be immediate. However, updates to the dependent FlowPath or Bladefeatures will happen only when you subsequently click the “Generate” button.

Contour Sketch Management

The contour sketches are managed just as normal sketches are managed in DesignModeler. To modify ameridional contour, you should first select the sketch in the tree view and then click the “Sketching” tab toopen the sketch toolbox. If you already have the sketch toolbox open, you can select a different active sketchfrom the toolbar drop-down list. For models with many different sketches, and for switching between editingone contour or another, this could be tedious. For this reason, it is possible to modify or delete existingedges in a sketch that is not the active sketch as long as it belongs to the same plane as the active sketch.However, newly created edges are added only to the active sketch, so it is imperative that you have theactive sketch selected appropriately when creating new edges.


ANSYS BladeEditor

BladeEditor Toolbars

BladeEditor utilizes three separate toolbars: one for feature creation, one for selection, and one for displaycontrol.

The following topics are discussedFeature Creation ToolbarActive Selection ToolbarDisplay Control Toolbar

Feature Creation Toolbar

The feature creation toolbar has icons for the BladeEditor specific features that can be added to the model(and that appear in the tree view).

The following icons exist in this toolbar:

DescriptionIcon

Creates an ImportBGD feature,which is used to import a Blade-

Import BGD

Gen file and construct a solidmodel of the blade and optionallythe hub and fluid zone. The flowpath and blade shape cannot beedited in BladeEditor, but the im-port can be refreshed if there areany changes to the BladeGen file.For details, see Importing Blades

from ANSYS BladeGen (p. 41).

Loads a BladeGen file and con-structs the FlowPath, CamThkDef,

Load BGD

Blade, and Splitter features so thatthe flow path and blade shapemay be edited in BladeEditor.

Creates a flow path (FlowPath)feature, which is used to define

FlowPath

the flow path for blade geometry(that is, the meridional shape ofthe passage). For details, seeFlowPath Feature (p. 28).

Creates a camberline/thickness(CamThkDef ) feature (a blade

CamThkDef

profile), which is used to constructa blade geometry. For details, seeCamberline/Thickness Definition

Feature (p. 30).

Creates a blade (Blade) feature,which is used to create the blade

Blade

bodies. For details, see Blade Fea-

ture (p. 34).




DescriptionIcon

Creates a splitter (Splitter) feature,which is used to create the splitter

Splitter

bodies. For details, see Splitter

Feature (p. 36).

Creates a Vista TF export (VistaTF-Export) feature for exporting the

VistaTFExport

flow path and blade geometry tothe Vista TF through flow analysistool. For details, see Export to Vista

TF (.geo) (p. 46).

Creates an ExportPoints featurefor exporting blade point data to

ExportPoints

TurboGrid or to a meanline file.For details, see Export to ANSYS

TurboGrid (p. 48) and Export as

Meanline Data (.rtzt file) (p. 47).

Creates a stage fluid zone (Stage-FluidZone) feature for generating

StageFluidZone

the blade passage bodies. Thestage fluid zone is a 3D fluid re-gion to support CFD analyses. Fordetails, see Stage Fluid Zone Fea-

ture (p. 38).

Creates a throat area (ThroatArea)feature for calculating the blade

ThroatArea

throat area. For details, see Throat

Area Feature (p. 39).

Opens the BladeEditor preferencesin the details view. For details, see

Preferences

User Preferences and Proper-

ties (p. 25).

Note that, because of limitations in the FlowPath, CamThkDef, and Blade features, the ‘Load BGD’ featuresupports loading BladeGen files with the following restrictions:

• Model

Only the ‘Angle/Thickness’ mode is supported.

• If loading multiple BladeGen files, the Beta Definition, ‘from Axial’ or ‘from Tangential’, must be consistentfor all files.

• Layers

Only specified span fraction layers are supported.

The Spanwise Calculation mode must be ‘Geometric’.

• Angle Definition

Only Theta and/or Beta definitions are supported, not End Angle.


ANSYS BladeEditor

Only General and Ruled Element spanwise distributions are supported.

At least one angle definition must exist on either the hub or shroud layer.

The Angle View Data Location must be 'Meanline'.

• Thickness Definition

Only the 'Normal to Meanline on Layer Surface' thickness data type is supported.

The 'vs. Cam' and '% Cam vs. % Cam' thickness specifications are not supported.

Only the General spanwise distribution is supported

At least one thickness definition must exist on either the hub or shroud layer.

• Meridional Profile

Only the 'Design Profile' is supported.

Active Selection Toolbar

The selection of the “active” angle and thickness view utilizes a toolbar similar to the sketch selection func-tionality. The toolbar consists of two combo boxes: one for the FlowPath/Blade selection and one for thelayer selection. The first combo box will enable you to select from all of the currently defined FlowPath andBlade features, while the second combo box will enable you to select from the available layers defined onthe active FlowPath.

For example, for a model that contains two FlowPath features (FlowPath1 and FlowPath2) with one Bladefeature defined on FlowPath1 and a Blade feature and Splitter feature defined on FlowPath2, the combobox would list the following:

FlowPath1

FlowPath1 Blade1

FlowPath2

FlowPath2 Blade2

FlowPath2 Splitter2

The FlowPaths and Blades are shown separately because the CamDef feature is defined in the context ofboth the FlowPath and the Blade, and therefore the view is context-specific.

Assuming there are five layers in the selected FlowPath/Blade, the Layer combo box would list the following:

Layer 1

Layer 2

Layer 3

Layer 4

Layer 5

Alternatively, if CamDef features were defined on layers 1 and 5, then the Layer combo box would list thefollowing:




Layer 1 CamDef1

Layer 2

Layer 3

Layer 4

Layer 5 CamDef2

Display Control Toolbar

The display control toolbar enables you to control display properties such as the angle/thickness graph vis-ibility and graph view actions such as “zoom fit”, etc.

Angle and Thickness Views

The Angle and Thickness Views let you see and modify the Camberline/Thickness definitions. These viewshave behavior similar to the views in BladeGen. Both views present the data for the active CamDef feature.See Active Selection Toolbar (p. 23) for more details on how the active CamDef feature is selected.

If the Blade feature or any of its parent features have been modified, the curves shown in the angle/thicknessviews, when displayed under the Blade feature, are updated when the model is regenerated.

The following topics are discussed:Angle ViewThickness View

Angle View

The angle view displays a graph of the Theta and Beta angle definition for the selected CamDef feature.Within this view, you can:

• Access a shortcut menu by right-clicking the mouse.

• Drag the control points defining the Theta/Beta curve (left-click on a control point and drag with themouse).

• Change the angle type: Theta or Beta (context menu).

• Change the curve type (context menu).

• Insert or delete points (context menu).

• Set control point coordinates (double-click a control point and edit the coordinate values in a dialogbox).

• View the coordinates of any location on a curve (hold the Ctrl key and left click any control point orline segment of a curve).

• Show all defining Theta/Beta curves in the current view (context menu).

• Show the second angle curve (beta or theta) in the current view (context menu).

• Pan the view (right-click and drag).

• Zoom in and out (middle-click and drag).

• Zoom in via a zoom box (hold the Alt key and left-click and drag from the top-left corner to the bottom-right corner of a rectangular region; drag in the opposite direction to re-fit the view).

• Change the x-axis display type: m, m’, %m, or %m’ (context menu).


ANSYS BladeEditor

• Read angle data points from a file or save points to a file (context menu). In a crude way, this enablescopying and pasting data from one CamDef feature to another, or to and from an external application,e.g. a spreadsheet.

• Convert the selected curve segment to a Bezier or spline curve of the specified order (context menu).

Note

When the meridional contours are changed, the angle data points are scaled relative to the percentm’-coordinate (% m-prime).

Note

X-axis value behaviour: preference used as default. Change of x-axis value will affect all layersviewed for a given Blade feature.

Thickness View

The thickness view displays a graph of the thickness definition for the selected CamDef feature. Within thisview, you can:

• Drag the points defining the thickness curve (mouse)

• Change the curve type: Bezier, cubic spline, piecewise-linear (context menu)

• Insert or delete points (context menu)

• Show all defining thickness curves in the current view (context menu)

• Zoom/Pan the view (mouse)

• Change the x-axis display type: m, m’, %m or %m’ (context menu)

• Read thickness data points from a file or save points to a file (context menu)

• Convert selected curve segment to Bezier or spline curve of specified order (context menu)

Note

When the meridional contours are changed, the thickness data points are scaled relative to thepercent m-coordinate (% m).

Note

X-axis value behavior: preference used as default. Change of x-axis value will affect all layersviewed for a given Blade feature.

User Preferences and Properties

The model properties are listed in the details view for the root node (along with the DesignModeler fileproperties.) Model properties are saved with the .agdb file. These properties include:

• Length Tolerance - Sketch edge tessellation tolerance in current length unit

• Angle Tolerance – Angle graph tolerance in degrees



User Preferences and Properties

• Beta definition (axial or tangential)

• Angle View – x-axis type

• Thickness View – x-axis type

• Show Advanced Properties – this specifies whether the advanced parameters or expert parameters areshown in the details view. This only applies to specific features, such as the Blade and Splitter.

Blade Editing Features

The BladeEditor toolbar icons related to creating/editing a blade are:

DescriptionIcon

Creates a flow path (FlowPath)feature, which is used to define

FlowPath

the flow path for blade geometry(that is, the meridional shape ofthe passage). For details, seeFlowPath Feature (p. 28).

Creates a camberline/thickness(CamThkDef ) feature (a blade

CamThkDef

profile), which is used to constructa blade geometry. For details, seeCamberline/Thickness Definition

Feature (p. 30).

Creates a blade (Blade) feature,which is used to create the blade

Blade

bodies. For details, see Blade Fea-

ture (p. 34).

Creates a splitter (Splitter) feature,which is used to create the splitter

Splitter

bodies. For details, see Splitter

Feature (p. 36).

Creates a Vista TF export (VistaTF-Export) feature for exporting the

VistaTFExport

flow path and blade geometry tothe Vista TF through flow analysistool. For details, see Export to Vista

TF (.geo) (p. 46).

Creates an ExportPoints featurefor exporting blade point data to

ExportPoints

TurboGrid or to a meanline file.For details, see Export to ANSYS

TurboGrid (p. 48) and Export as

Meanline Data (.rtzt file) (p. 47).

Creates a stage fluid zone (Stage-FluidZone) feature for generating

StageFluidZone

the blade passage bodies. Thestage fluid zone is a 3D fluid re-gion to support CFD analyses. For


ANSYS BladeEditor

DescriptionIcon

details, see Stage Fluid Zone Fea-

ture (p. 38).

Creates a throat area (ThroatArea)feature for calculating the blade

ThroatArea

throat area. For details, see Throat

Area Feature (p. 39).

The following topics will be discussed:Flow Path Contour CreationFlowPath FeatureCamberline/Thickness Definition FeatureBlade FeatureSplitter FeatureStage Fluid Zone FeatureThroat Area Feature

Flow Path Contour Creation

The main elements of a multi-blade row machine are the flow path and the individual blade rows, as shownin Figure : Flow Path and Blade Row Concepts (p. 27).

Figure: Flow Path and Blade Row Concepts

The first step in creating new blade row geometry is creating the flow path contours that define the hub,shroud, inlet and outlet. The flow path contours are defined by sketch edges, which can be created usingthe existing DesignModeler sketch tools. Each contour (hub, shroud, etc.) should be defined in a separatesketch. This implicitly identifies all the edges belonging to a given contour. All contour sketches are expectedto lie on the same Plane feature. Not only will this guarantee that the contours are coplanar, it will enableyou to apply constraints and dimensions between sketches.



Flow Path Contour Creation

Note

• Contour sketches must be created on the (global) ZX-plane. The local X and Y axes on thesketch plane correspond to the global Z and X axes, respectively. The local X axis correspondsto the machine axis and the local Y axis corresponds to the radial coordinate axis. Con-sequently, all flow contours in the sketch must have positive Y coordinates.

• It is advisable that you turn off the sketch global autoconstraint setting. Click the Sketching

tab, click the Constraints toolbox, click Auto Constraints and clear the Global check box.Having this global constraint turned on may cause undesirable constraints to be added tothe LayerContour edges.

• The hub, shroud, inlet, and outlet contour end points must be coincident.

FlowPath Feature

The FlowPath feature specifies the flow path. The contour sketches described in Flow Path Contour Cre-

ation (p. 27) are used in the definition of this feature. The FlowPath feature also creates the constant-span-fraction layers used to define the blade profiles, and automatically creates the LayerContour sketch, whichshows the locations of the layers. The feature properties are listed in the table below. Note that all itemsunder each bold heading in the table are grouped under that heading.

Details of [Feature Name]

[Name]FlowPath

[Pump | Centrifugal Compressor |Axial Compressor | Fan | Radial

Machine Type

Turbine | Axial Turbine | HydraulicTurbine | Other | Undefined]

[Right-handed | Left-handed]Theta Direction

[Sketch selection]Hub Contour

[Sketch selection]Shroud Contour

[Sketch selection]Inlet Contour

[Sketch selection]Outlet Contour

[Yes | No]Hub Cut?

[Sketch selection](If Hub Cut = Yes)

Hub Cut

[Yes | No]Shroud Cut?

[Sketch selection](If Shroud Cut =Yes)

Shroud Cut

Implicitly defined number of layersNumber of Layers

Layer: 1

Fixed SpanLayer Type

0Span Fraction

Layer: 2


ANSYS BladeEditor


[0 < Value < 1]Span Fraction

Layer: 3


[0 < Value < 1]Span Fraction

Layer: 4


1Span Fraction

The Machine Type is used by downstream applications, for example in CFD-Post, for determining the appro-priate default post-processing report. The Theta Direction specifies the interpretation of the theta directionfor the CamDef angle definitions. The theta direction can be specified as either right-handed or left-handedrelative to the direction of the global z-axis (the machine axis).

By default, the flow path starts with two layers: one for the hub and one for the shroud. You can insert ordelete layers using a shortcut menu in the details view. Layers on which CamDef features are defined cannotbe deleted. The first and last layers must be at span fractions of 0 and 1, respectively; these will always becreated and cannot be deleted or changed. A given blade does not need to have defined profiles on alllayers. The layers are defined in the context of the FlowPath feature for consistency between blade rows.

The only Layer Type in version 12 is Fixed Span. This requires that you specify the span fraction for the givenlayer.

You can create the FlowPath feature automatically via a BladeGen import, or manually. In either case, youcan change the sketch selections once the feature has been created. You must ensure that the contours areproperly connected to form a closed loop. This means that the endpoints of adjacent contours must be co-incident.

In the tree view, the parent sketches (HubContour, ShroudContour, etc.) and child sketch (LayerContour)should appear as sub-features of the FlowPath feature. These sketches will also appear under the parentmeridional plane.

The following topic will be discussed:Flow Cut

Flow Cut

The FlowPath feature has optional hub cut and shroud cut properties to support trimming the flow pathfor a 'flow cut'. An example is if you have a base centrifugal compressor blade design that is used for a rangeof compressors. In this case, the FlowPath and Blade features would define the base blade geometry. Youthen wish to use the same blade but in a different size compressor, so the blade height needs to be trimmed.The flow cut would be used to define the final flow path boundaries, and would trim the height of all bladesin the flow path.

The flow cut affects all blades that reference the flow path. The flow cut properties take as input the sketchcontours that define the flow cut. The additional feature properties are in a group below the Outlet Contourproperty. The property group is defined below.

To make best use of this feature, sketches should support the reading of external point data, in particularpoint data exported from CFD-Post. This lets you choose a flow “streamline” from a Vista TF or CFX analysis



FlowPath Feature

and use it to trim the flow path. Currently, creating spline curves from external point data is only supportedvia script.

Camberline/Thickness Definition Feature

The Camberline/Thickness Definition (CamDef ) feature provides the angle and thickness distribution on aselected layer contour. This definition is a child of the FlowPath feature and a parent of the Blade feature.The angle and thickness distributions are specified versus normalized coordinates corresponding to 0% atthe leading edge and 100% at the trailing edge. A CamDef feature can be referenced by more than oneBlade feature. Also, a CamDef feature can be copied from one layer to another.

Each CamDef feature will appear as a sub-feature of the parent FlowPath in the tree view. When a CamDeffeature is referenced by a Blade, it will also appear as a sub-feature for that Blade. This is consistent withthe tree view behavior for sketches, which provide a similar function to the CamDef features.

The CamDef feature properties are as follows:


[Feature Name]Camberline Defini-tion

[FlowPath feature selection]Flow Path

[Index Value]Layer Number

Camberline Details

[Yes | No]Angle Definition?

[Theta | Beta]Angle DefinitionType

[Leading Edge | Trailing Edge](For Beta defini-tion only)

Theta Reference

[Value]Theta @ LE

or

[Value]Theta @ TE

[Camberline | Side 1 | Side 2]Angle Data Loca-tion

[Parameter Values][Parameter List]

Thickness Details

[Yes | No]Thickness Defini-tion?

[Normal to Cambersurface | Nor-mal to Camberline on Layer sur-face | Tangential on Layer surface]

Thickness Defini-tion Type

The angle and thickness data that is associated with a CamDef feature is displayed in the angle/thicknessgraph view.


ANSYS BladeEditor

The CamDef feature saves the angle data as % m-prime and the thickness data as % m. After a CamDef isapplied to the portion of a layer between LE and TE of a blade/splitter, the local angle data and thicknessdata are created for the blade/splitter. These local data are represented as m-prime and m values which areconverted from % m-prime and % m.

If the Angle Definition Type is set to Theta, then the specified angle curve is used as the theta definition forthe camberline. If the Angle Definition Type is set to Beta, then the angle curve is used as the Beta definition,and the theta definition is derived by integrating the Beta curve with the specified Theta Reference. TheTheta Reference can be specified at either the leading edge or the trailing edge of the blade for which thecamberline is applied.

When a CamDef feature is selected on the feature tree, its angle data will be displayed on the angle graphand its thickness data will be displayed on the thickness graph.

When the data in angle or thickness graph pane is modified, the data inside the CamDef feature will bechanged to reflect the modification. Also, if any blade/splitter refers to the CamDef feature, all theseblade/splitter should update their local angle/thickness data.

If you select 'No' for the Angle Definition or Thickness Definition parameter, then no curve data for thisdefinition will be available for editing in the graph view, and this definition will be ignored in the corres-ponding angle or thickness surface calculation. Furthermore, if the selected CamDef feature is a sub-featureto a Blade, then the graph view will show the interpolated angle or thickness data for this blade, otherwise




no data will be shown in the graph. The interpolated data is for display only and cannot be edited; thecontext menu commands for editing are hidden in this case.

If you subsequently select 'Yes' for the Angle Definition or Thickness Definition parameter, then the curvedata will be initialized by interpolation if possible, otherwise it will be initialized to default data (two points).Interpolation will occur if the selected CamDef feature is a sub-feature to a Blade, so that the data can beinterpolated from the blade definition. If the CamDef feature is reference by more than one blade, then theblade that is selected (above the CamDef feature) will be used to interpolate the data.

If you want to insert a CamDef feature into an existing Blade feature without initially affecting the shape ofthe blade, the ‘Insert/Interpolate Camberline’ operation can be used. Multi-select a new CamDef featurealong with the Blade feature, right-click, and select ‘Insert/Interpolate Camberline’. The angle and thicknessdata of the selected CamDef feature will then be updated by interpolating from the existing blade.

If you specify a curved leading or trailing edge contour, you must have at least three angle and/or thicknessdefining camberlines to create the desired blade shape. Furthermore, if you specify a cut-off leading ortrailing edge and you do not have sufficient camberlines to follow the edge curvature, then the cut-off op-eration will fail. Adding additional camberline definitions (especially where the leading/trailing edge curvedeviates the most from the blade shape) should fix this problem.

The following topics are discussed:Importing and Exporting Angle Definition DataImporting and Exporting Thickness Definition DataConverting Curves to Bezier or SplineConverting Angle Definition DataForcing Interpolation of the Definition Data

Importing and Exporting Angle Definition Data

There is an import/export points mechanism for the Angle Definition to support the manipulation of theAngle Definition points outside of BladeEditor, and to provide a means to read data from a file producedexternally. In the Angle View, the context menu operation 'Read Points' lets you replace the active curvedata points from the data in a text file called a '.ha' file. The context menu operation 'Save Points' lets yousave the active data points to a '.ha' text file. These options are available only if the Angle Definition is active,i.e. set to 'Yes'.

The first line in the '.ha' file specifies the number of points. Subsequent lines in the file, one for each datapoint, contain the point coordinate values 'h, a', where 'h' is the horizontal or x-axis value and 'a' is the anglevalue. The point coordinates correspond to the defining points for the angle definition curve, which maybe either Theta or Beta, in degrees, versus m-prime, % m-prime, m or % m.

When reading the '.ha' file, the data point coordinates will be interpreted based on the Angle DefinitionType and the selected x-axis type. If the Angle Definition Type is set to Theta, then the angle values will beinterpreted as Theta values. Otherwise, the angle values will be interpreted as Beta values. If the x-axis isset to m-prime or % m-prime, then the 'h' coordinates for the data points will be treated as % m-prime values,and the values will be normalized based on the first and last data points so that the values start at zero andend at 100%. If the x-axis is set to m or % m, then the 'h' coordinates for the data points will be convertedto m values by normalizing based on the first and last data points and then multiplying by the maximumm on the layer. These values will then be converted to % m-prime. The existing angle curve data for allsegments will be replaced by a single curve segment with the data from the '.ha' file, and the curve typewill be set to 'cubic spline'.

When you choose 'Save Points', the defining points for all curve segments will be written sequentially tothe file starting with the leading edge point and ending at the trailing edge point. The 'h' coordinates will


ANSYS BladeEditor

be written in the value corresponding to the selected x-axis type. If the Angle Definition Type is set to Theta,then the Theta values will be written as the angle values. Otherwise, the Beta values will be written as theangle values.

You can select the x-axis scale as m-prime, m, or % m only if the selected CamDef feature is defined in thecontext of a Blade feature.

Importing and Exporting Thickness Definition Data

There is an import/export points mechanism for the Thickness Definition to support the manipulation of theThickness Definition points outside of BladeEditor, and to provide a means to read data from a file producedexternally. In the Angle View, the context menu operation 'Read Points' lets you replace the active curvedata points from the data in a text file called a '.ht' file. The context menu operation 'Save Points' lets yousave the active data points to a '.ha' text file. These options are available only if the Thickness Definition isactive, i.e. set to 'Yes'.

The first line in the '.ht' file specifies the number of points. Subsequent lines in the file, one for each datapoint, contain the point coordinate values 'h, t', where 'h' is the horizontal or x-axis value and 't' is thethickness value. The point coordinates correspond to the defining points for the thickness definition curvein the length unit being used in DesignModeler, versus m-prime, % m-prime, m or % m.

When reading the '.ht' file, the data point coordinates will be interpreted based on the selected ThicknessDefinition Type and the x-axis type. If the x-axis is set to m or % m, then the 'h' coordinates for the datapoints will be treated as % m values, and the values will be normalized based on the first and last datapoints so that the values start at zero and end at 100%. If the x-axis is set to m-prime or % m-prime, thenthe 'h' coordinates for the data points will be converted to m-prime values by normalizing based on the firstand last data points and then multiplying by the maximum m-prime on the layer. These values will then beconverted to % m. The existing thickness curve data for all segments will be replaced by a single curvesegment with the data from the '.ht' file, and the curve type will be set to 'cubic spline'.

When you choose 'Save Points', the defining points for all curve segments will be written sequentially tothe file starting with the leading edge point and ending at the trailing edge point. The 'h' coordinates willbe written in the value corresponding to the selected x-axis type, while the thickness coordinates will bewritten in the value corresponding to the selected Thickness Definition Type.

You can select the x-axis scale as m-prime, m, or % m only if the selected CamDef feature is defined in thecontext of a Blade feature.

Converting Curves to Bezier or Spline

This feature lets you convert a curve segment in either the Angle or Thickness views to an equivalent splineor Bezier curve with a specified number of points. The new curve is an approximation of the original curve,and the error in the approximation depends on the complexity of the original curve and the specifiednumber of points for the new curve. This operation is very helpful for simplifying a curve with many points,either because it was imported or was interpolated.

The context menu items are: 'Convert to Bezier' and 'Convert to Spline'. They are available in both the Angleand Thickness views. When choosing either of these options, you are asked to specify the number of pointsfor the new curve in a dialog box. After clicking OK, you are required to select the curve segment to convertin the graph view. The curve will be converted immediately following your selection.




Converting Angle Definition Data

If you select the CamDef feature at the root tree level and change the Angle Definition Type, e.g. to Betafrom Theta, then the input data in the graph will be kept as is, and will be taken as the data for the newangle type. If you switch from Theta to Beta, the Theta reference will be defaulted to zero. This switch willlikely change the shape of the camberline.

If you select the CamDef feature under a Blade feature and change the Angle Definition Type, then the angledata is converted to the new type. This conversion will try to retain the shape of the camberline by interpol-ation. Thirty points are used in the interpolated curve.

Forcing Interpolation of the Definition Data

You may want to insert a CamDef feature into an existing blade without initially changing the shape of theblade. In this case an interpolation is required. You should multi-select the CamDef feature to be insertedalong with the Blade feature, and right-click “Insert and interpolate Camberline”. This would insert theCamDef feature into the selected Blade and re-initialize the data from the angle and thickness definitions.Which angle data to be interpolated would be determined by the Angle Definition Type in the CamDeffeature. The selected CamDef feature cannot be referenced by another blade.

Blade Feature

The Blade feature is the geometry feature that is responsible for creating a blade or blade set. This featuredefines the key properties of the blade, such as the blade type and the leading and trailing edge locationand shape. It references the angle and thickness definitions to define the blade profiles. A given Blade feature(and its child Splitter features) must not overlap with other Blade features (and their child Splitter features)within a given FlowPath.

The feature properties are as follows:


[Feature Name]Blade

[CamDef selections]Camberline Defini-tions

[Rotor | Stator]Type

[Int Value]Number of BladeSets

[General | Ruled Element]Surface Construc-tion

[Value]Blade Extension(%)

Leading Edge Details

[Sketch selection]Contour

[Ellipse | Cut-off | Square]aType

[Value]Ratio at Hub (forEllipse only)

[Value]Ratio at Shroud(for Ellipse only)

Trailing Edge Details


ANSYS BladeEditor

[Sketch selection]Contour

[Ellipse | Cut-off | Square]Type

[Value]Ratio at Hub (forEllipse only)

[Value]Ratio at Shroud(for Ellipse only)

Advanced Properties (Hidden by default)

[Int Value]Number of PointsAlong the Blade

[Int Value]Number of Pointsfor LE (for Ellipseonly)

[Int Value]Number of Pointsfor TE (for Ellipseonly)

Camberline/Thickness Definitions: [number]

[CamDef reference]Camber/Thick Def.1

[CamDef reference]Camber/Thick Def.2

aNote that you cannot specify a perfectly sharp trailing edge. As a workaround, you can specify a square trailing edge with a small, but finite,thickness (for example, 0.05 mm).

The Type property specifies whether the blade is a rotating or stationary component. The FlowPath selectionis the reference to the FlowPath feature, which is mandatory. The CamDef selections are the references tothe CamDef features that describe the angle and thickness definitions; these are also mandatory. At leastone CamDef with a specified angle definition must be selected to define the Blade. If only one angle defin-ition is specified, the angle definition must be given on either the hub or the shroud. The same rule appliesfor the thickness. If the Surface Construction type is set to “Ruled Element”, then only two CamDefs may beselected, and they must be defined at the hub and shroud. Once the CamDefs have been selected, they willappear (for reference only) under the section at the bottom of the list "Camberline Definitions".

In the tree view, CamDef features appear as sub-nodes of the Blade/Splitter feature.

When the CamDef feature is highlighted from the sub-node position of Blade/Splitter feature, the anglecurve and thickness curve can be displayed as percentage M/Mp values and actual Mp/M values based oncurrent blade/splitter.

When the curve in angle or thickness graph pane is modified, the CamDef feature is updated simultaneously.The display for blades/splitters referring to the CamDef feature may not be updated until the generation isfinished.

If you want to insert a CamDef feature into an existing Blade feature without initially affecting the shape ofthe blade, the ‘Insert/Interpolate Camberline’ operation can be used. Multi-select a new CamDef featurealong with the Blade feature, right-click, and select ‘Insert/Interpolate Camberline’. The angle and thicknessdata of the selected CamDef feature will then be updated by interpolating from the blade definition.



Blade Feature

Splitter Feature

This feature creates a new blade relative to an existing (main) blade such that the new blade (or splitter)shares the same Flow Path and blade count, and is generally assumed to be part of the same blade row.The base object of this feature is the selected Blade feature; only one Blade feature can be selected perSplitter feature.

The Splitter feature can be one of two forms: a cloned splitter or an independent splitter. The form is specifiedin the feature properties. Once the feature has been created, you cannot change the type.

The following topics will be discussed:Cloned SplitterIndependent Splitter

Cloned Splitter

A cloned splitter shares the same blade shape as the main blade, but is offset in theta from the main blade.Typically, a cloned splitter is trimmed by the BladeTrim feature to shorten the blade, e.g. the splitter in acentrifugal compressor.



[Feature Name]Splitter

ClonedType

[Blade feature selection]Main Blade

[Pitch Fraction | Specified Angle]Offset Type

[Value: 0-1]Pitch Fraction

or

[Value]Angle

The Offset Type specifies how the splitter will be offset relative to the main blade. If “Specified Angle” isselected, then the angular offset of the cloned splitter blade relative to the main blade is specified directly.If “Pitch Fraction” is selected, then the pitch fraction as a value between 0 and 1 is specified. The pitchfraction represents the fraction of distance between two adjacent main blades. The actual angular offset is:

offset = pitch fraction * 2 * pi / n

where n is the number of main blades.

Independent Splitter

An independent splitter can have a completely different shape than the main blade, but it still shares thesame blade count and has a fixed offset from the main blade. The feature properties are nearly identical tothe Blade feature except for the additional main blade reference and offset value.

The properties are as follows:



ANSYS BladeEditor

[Feature Name]Splitter

IndependentType

[Blade feature selection]Main Blade

[Pitch Fraction | Specified Angle]Offset Type

[Value: 0-1]Pitch Fraction

or

[Value]Angle

[Hub at Leading Edge | Hub atTrailing Edge]

Offset Reference(Only for PitchFraction)

[CamDef selections]Camberline Defini-tions

[General|Ruled Element]Surface Construc-tion

...

(the remaining details are the same as for the Bladefeature)

The interpretation of the Offset Type is different for an independent splitter than for the cloned splitter. If“Specified Angle” is selected, then the angular position of the splitter will be determined by the cambersurface theta, shifted by the specified angle. If “Pitch Fraction” is selected, then you enter the pitch fractionas a value between 0 and 1, for the cloned splitter. However, because an independent splitter can have adifferent shape than the main blade, an Offset Reference must be specified. This determines how the splitterwill be positioned relative to the main blade. The angular offset and the offset reference determine the ref-erence theta for the splitter blade.

When “Hub at Leading Edge” is selected for the Offset Reference, the reference theta and the camberlinelocations are calculated as follows:

1. An offset reference meridional location is calculated at the intersection of the hub contour and thesplitter leading edge contour.

2. For the offset meridional location, the main blade theta value is calculated from the main blade cam-bersurface.

3. The reference theta is then calculated by adding the angular offset (from the pitch fraction or specifiedangle) to the main blade theta value.

4. All splitter camberline theta values are offset internally so that the splitter hub camberline starts atthe reference theta.

Alternatively, when “Hub at Trailing Edge” is selected for the Offset Reference, the reference theta and thecamberline locations are calculated as follows:

1. An offset reference meridional location is calculated at the intersection of the hub contour and thesplitter trailing edge contour.

2. For the offset meridional location, the main blade theta value is calculated from the main blade cam-bersurface.



Splitter Feature

3. The reference theta is then calculated by adding the angular offset (from the pitch fraction or specifiedangle) to the main blade theta value.

4. All splitter camberline theta values are offset internally so that the splitter hub camberline ends at thereference theta.

When a BladeGen model with splitters is imported, the theta values shown for the splitter camberlines mayappear to differ in BladeEditor. The reason is that BladeGen always calculates the splitter reference thetausing a meridional location at the main blade leading edge rather than at the splitter blade leading edge.When the splitter camberline definitions are imported they are converted to preserve the blade positionand shape, and therefore the point data for the definitions may differ.

Stage Fluid Zone Feature

The “fluid zone” represents the 3D fluid region within the flow passage, and is used to define the extent ofthe CFD domain. In release 11.0, a fluid zone was automatically created for each ImportBGD feature, whichincluded the fluid region around a single blade row. For multiple blade rows, the fluid zone must includeseparate regions for, and have distinct interfaces between, each blade row.

In release 12.0, a new StageFluidZone feature takes as a reference the selected FlowPath feature, and createssolid bodies for the fluid region in every blade row of the flow path. The first stage fluid zone in the flowpath will start at the inlet contour and extend to the first interface (or to the outlet contour if there is onlyone blade row). The last stage fluid zone starts at the last interface and extends to the outlet contour. Allintermediate stage fluid zones start and end at the interfaces adjacent to the blade row. The individualbodies are “frozen” so that they are not merged to adjacent solid bodies, including adjacent stage fluid zonebodies. (Individual bodies can be suppressed or hidden using existing DM functionality.) The StageFluidZonefeature respects any BladeClearance, BladeTrim, or FlowCut features that have been applied to the FlowPathor blade rows prior to the StageFluidZone feature. All active bodies (blades, hub, etc.) are subtracted fromthe fluid zone.

The stage fluid zone upstream and downstream interfaces are located by default halfway between the closestextents of the adjacent blade rows. For this to work, the StageFluidZone feature assumes that there is nooverlap between adjacent blade rows; the StageFluidZone feature reports an error if this condition is violated.(Overlapping blade designs should be created using a combination of the Blade and Splitter features.) Youmay adjust the relative location of the interface by using one value in the range 0-1.


Table 1 Details View for StageFluidZone Feature


[Feature Name]StageFluidZone


[Yes | No]Create Named Se-lections

Interface Detail 1:

[Value: 0-1, default 0.5]aInterface Location

Interface Detail 2:

[Value: 0-1, default 0.5]aInterface Location

a0 corresponds to the aftmost trailing edge of the set of blades in the upstream blade row. 1 corresponds to the foremost leading edge ofthe set of blades in the downstream blade row.


ANSYS BladeEditor

The Create Named Selections property determines whether the feature will automatically create named se-lections for each stage fluid zone. The Interface Details groups are created dynamically depending on thenumber of interfaces involved (number of blade rows less one.)

Named selections are created automatically for each blade row of the StageFluidZone. The naming conventionis Hub_[Main Blade Name], Shroud_[Main Blade Name], Blade_[Blade Name], etc. where Main Blade Nameis the name of the main blade in the given blade row. For the Blade_ regions, each blade in the blade rowwill have a separate region defined.

Named selections will not appear in DesignModeler, but they will appear if you load the .agdb file into theMechanical application or the Meshing application, provided that you have set the properties of the Geometrycell (on the Project Schematic page in ANSYS Workbench) as follows:

• Attributes is selected.

• Attribute Key string is cleared.

(This setting appears when Attributes is selected.)

• Named Selections is selected.

You can make the Geometry cell settings this way by default by selecting Tools > Options from the ANSYSWorkbench main menu, browsing to the Geometry Import branch, and setting CAD Attributes (same as At-tributes), CAD Attributes > Filtering Prefixes (same as Attribute Key), and Named Selections.

Note

If the StageFluidZone periodic interfaces do not appear to be trimmed appropriately on the hubor shroud boundaries, you can try increasing the Blade Extension property for the correspondingblade feature to remedy the problem. The StageFluidZone feature uses this property to controlhow the periodic interfaces are created.

Throat Area Feature

The throat area (ThroatArea) feature is used to calculate and display the throat surface(s) for one or moreselected blade rows. The calculation is normally updated each time you issue the Generate command. Thefeature may be suppressed to avoid the calculation time when it is not needed, or the feature may be deletedif it is no longer needed.


Table 2 Details View for ThroatArea Feature


[Feature Name]ThroatArea

[Blade feature selection]Blade

[Leading Edge | Trailing Edge |Minimum Area]

Location

[Value]Throat Surface Ex-tension

(Advanced Prop-erty)



Throat Area Feature

Throat Details:

[Value]Area

[Value]Layer 1 Length

[Value]Layer 2 Length

...

...

...

Blade items arelisted for all selec-ted blades.

The input property, Blade, is a Blade feature selection used to indicate the blade row. The Location propertyspecifies the region for which to calculate the passage area. The choices are as follows:

• Leading Edge - computes the passage area in the region of the main blade leading edge.

• Trailing Edge - computes the passage area in the region of the main blade trailing edge.

• Minimum Area - computes the minimum passage area considering all blades in the blade row.

The Leading Edge option can report the throat width for a throat location that is a considerable distanceaway from the leading edge. A similar statement applies for the Trailing Edge option.

The minimum area calculation uses a minimization algorithm based on the blade profiles on the designlayers of the blade. If there are only one or two defining layers, then additional layers will be inserted forthe purpose of the calculation.

The output property group contains the throat area and the throat lengths for each layer defined in theflow path.

The throat surface is displayed in the viewer as a frozen sheet body. The Throat Surface Extension propertyenables you to control the surface extension to ensure that the throat surface is cut by the blade bodiesproperly. This is an advanced property and it is shown only if the Show Advanced Properties preference isselected.

Note

The minimization calculation of the throat surface area uses the raw blade profile data from theBlade feature and not the final solid model. The actual throat surface area is calculated from thesolid model.

Note

For Vista TF users: The throat widths are not added to the Vista TF geometry file. The throat datacan be added manually. See the .geo file format description in Specification of the Geometry Data

File (*.geo) (p. 83).


ANSYS BladeEditor

Importing Blades from ANSYS BladeGen

BladeEditor provides a geometry connection between BladeGen and DesignModeler. Reasons for importingBladeGen blades into DesignModeler include:

• ANSYS BladeGen can output geometry in many different point data formats, but its surface output inIGES format is cumbersome to use.

• BladeGen does not produce a solid model in a standardized format such as Parasolid.

• You can combine an imported blade with other CAD geometry imported via one of the many Design-Modeler-supported CAD file formats.

Through BladeEditor, one or more BladeGen models can be linked into a DesignModeler session, so thatany changes to the BladeGen models will be reflected in DesignModeler the next time you update theGeometry cell.

When you import a BladeGen model, BladeEditor does the following:

• constructs blade surfaces

• creates a solid model for the blades and hub

• creates 2-D sketches for the meridional contours and non-flow-path hub geometry

• creates periodic fluid zones

The preferred method of importing a BladeGen file is to create a link from the Blade Design cell of a BladeGensystem to the Geometry cell. This link maintains the data transfer relationship between the two cells. Thedesired import options should be set in the Blade Design cell properties. (See Table 1: BladeGen Blade Design

Cell Properties (p. 14) for more information.) After you make the link, the Geometry cell should be updatedto process the imported geometry.

Note

If you edit the Geometry cell before updating it, then the Import BGD feature details that areshown in BladeEditor may not accurately reflect the Blade Design cell properties. To refresh the

Import BGD feature properties, click in BladeEditor. It is not recommended that youedit the Import BGD properties inside BladeEditor because they will be overwritten by the prop-erties from the Blade Design cell the next time you update the Geometry cell.

Alternatively, you can import a BladeGen file from outside the project. To do this, click in theBladeEditor toolbar. When you click this icon, you will be prompted for the location and name of theBladeGen (.bgd ) file. Once the filename is selected, the details view will let you select the properties forthe import. These properties are listed in Table 3: Properties for the Import BGD File Feature (p. 42). As with




other DesignModeler feature properties, you can double-click in a property value box to change the selectionto the next choice, or single-click on the property and select the value from the drop-down list.

Table 3 Properties for the Import BGD File Feature

FunctionDefault

Value

Property

This property defines name of the import feature.ImportBGD#ImportBGD

This property defines the name and path of the imported.bgd file. You can change the source to a new .bgd fileif Refresh is set to Yes .

(selectedBGD File)

Source

You may change the value of this property to the intendedBladeGen model length unit if the latter does not match

(default isthe Design-

Unit Prefer-ence

the DesignModeler length unit. If the BladeGen modelModelerlength unit) length unit is specified as “Unknown” (in the BladeGen

model properties), then BladeEditor will interpret themodel as having the length unit specified here, and willprocess the model by converting from this unit into theDesignModeler length unit. Otherwise, the unit specifiedhere will be ignored, and the model will be converted fromthe unit specified in the .bgd file into the DesignModelerlength unit. It is recommended that you specify a lengthunit in BladeGen so that this information is stored in the.bgd file.

Make sure that the length unit specified here is appropriatefor the model. If the BladeGen dimensions are too small,DesignModeler may fail to import the BladeGen model.

If this property is set to Yes , then BladeEditor will createa HubProfile sketch for the non-flow path hub geometry,and will create a revolved body feature called HubBody .

YesCreate Hub

This property defines the default line offset (in the preferredlength unit) for creating the initial HubProfile sketch.

1 (Inch)Hub Offset

Note that this property is available only if Create Hub isset to Yes .

If this property is set to All , then BladeEditor will createall the blades using the number of blades specified in theBladeGen model.

AllCreateBlades

If this property is set to 1, then only the first blade will becreated.

If this property is set to No, then BladeEditor will create theblade with four faces corresponding to the leading edge,

YesMerge BladeTopology

pressure side, trailing edge and suction side. This can makeit easier to create a structural mesh for the blades in theMechanical application.

If this property is set to Yes , then the blade faces will bemerged where they are tangent to one another.


ANSYS BladeEditor

FunctionDefault

Value

Property

If this property is set to Streamwise , then BladeEditorwill loft the blade surfaces in the streamwise direction

StreamwiseBlade LoftDirection

through curves that run from hub to shroud. This is thedefault because the surface is more well defined, especiallyfor flank-milled blades.

If this property is set to Spanwise , then BladeEditor willloft the blade surfaces in the spanwise direction throughthe blade profile curves.

This property specifies whether a shroud clearance is cre-ated. If No is selected, then no shroud clearance is created.

NoCreateShroudClearance To create a shroud clearance, choose either Relative

Layer or Absolute Layer . The blade(s) will be trimmedoff at the selected BladeGen output layer, and the layercontour will be created in the LayerProfile sketch.

If Relative Layer is selected, then the selected Layer

Number is relative to the shroud layer, e.g., 1 implies thefirst layer closest to the shroud layer, 2 implies the secondclosest layer to the shroud, etc.

If Absolute Layer is selected, then the selected layerindex counts up from the hub layer, which is zero.

This property defines the selected layer index for the shroudclearance.

1Layer Num-ber

Note that this property is available only if Create Shroud

Clearance is selected.

If this property is set to Yes , then BladeEditor will createa StageFluidZone body for the flow passage, and an

YesCreate FluidZone

Enclosure feature to subtract the blade body. The resultingEnclosure can be used for a CFD analysis of the blade pas-sage.

If this property is set to Yes , then BladeEditor will createNamedSelections (regions) for the typical faces of the

YesCreateNamed Se-lections blade passage, i.e., Blade , Hub, Shroud , Inflow , Out-

flow , PeriodicA and PeriodicB . These NamedSelec-tions can be used as selection groups in other ANSYSWorkbench applications, e.g., as regions in CFX-Mesh.

Note that this property is available only if Create Fluid

Zone is set to Yes .

This property defines the surface extension length (as apercentage of the average hub to shroud distance) for the

2Blade Exten-sion (%)

blade surfaces. These surfaces are extended and thentrimmed to the MasterProfile sketch to ensure thatthe blade solid correctly matches the hub and shroudcontours.




FunctionDefault

Value

Property

This property defines the surface extension length (as apercentage of the average hub to shroud distance) for the

5Periodic SurfExtension(%) periodic surfaces. These surfaces are extended to ensure

that the StageFluidZone is properly cut.

This property specifies the style of the periodic interfacesurfaces.

Three PiecesPeriodic SurfStyle

If Three Pieces is selected, then the periodic surface iscreated in three connected pieces: one upstream of theblade, one within the passage, and one downstream of theblade. This style can better accommodate highly curved ortwisted blades, and is similar to the ANSYS TurboGrid styleof periodic surface.

If One Piece is selected, then the periodic surface is cre-ated as a single surface.

Note that this property is available only if Create Fluid

Zone is set to Yes .

This property specifies whether the imported BladeGenmodel should remain linked to the DesignModeler session.

YesRefresh

If this property is set to Yes , then when the DesignModelerGenerate button is clicked, BladeEditor will check to see ifthe BladeGen file has changed. If the BladeGen file has beenmodified, BladeEditor will reload the file. If the BladeGenfile has moved or has been deleted, BladeEditor will switchthis property to No and will leave the blade geometry un-changed.

If this property is set to No, then BladeEditor will not reloadthe BladeGen file when the DesignModeler model is regen-erated.

Once these properties have been set, click the Generate button, and the BladeGen model will be imported.

The following features will then be created in the tree view:

• MerPlane : this plane is a copy of the Z-X plane; it is the plane on which the blade design sketchesare created.

– MasterProfile : a sketch defining the hub, shroud, leading edge, trailing edge, inflow and outflowboundaries of the blade passage (imported from the .bgd file) will be created. This sketch is usedduring the creation of the blade bodies, and can be used to create the fluid zone. You should notmodify this sketch.1

– BladeProfile : a sketch defining the locations of the leading and trailing edges for the mainblade will be created.

1This constraint is to prevent the MasterProfile and the blades from becoming inconsistent, because the blade surface datacomes from BladeGen.


ANSYS BladeEditor

– HubProfile : a sketch defining the hub body will be (optionally) created. This sketch can bemodified; however, you should take care to ensure that the sketch loop remains intact or the hubbody will fail to regenerate.

HubBody - (Optionally) the HubProfile sketch is revolved to create the HubBody feature in thetree view.

• BladeBody - The blade surface data is imported and lofted in DesignModeler to create the BladeBodyfeature in the tree view.

• StageFluidZone - (Optionally) the MasterProfile sketch is revolved and cut into a sector by theperiodic surface to form the StageFluidZone body. This feature forms a sector of the fluid volumearound a single blade, but the blade has not been removed from the volume.

• Enclosure - When the StageFluidZone is created, the blade (and any other connected geometry)is removed from the StageFluidZone body by the Enclosure feature.

• Named Selections - These are the labeled regions on the final Enclosure body: Blade , Hub, Shroud ,Inflow , Outflow , PeriodicA and PeriodicB .

Loading and Modifying Blades from ANSYS BladeGen

If you create a blade from scratch in BladeEditor, or if you convert a BladeGen BGD file into BladeEditor

features (by clicking ), then you can modify the blade by editing any of the features in the TreeOutline. If you have imported the blade from BladeEditor, the blade will be dependent on the BladeGenBGD file, but you can still modify the HubProfile sketch that appears under the associated MerPlanefeature.

Note

If you edit the hub sketch, make sure to maintain a closed edge loop when modifying this sketchor the hub body will fail to be generated. You can check the loop while editing the sketch byright-clicking in the viewer, choosing Select Loop/Chain and then selecting an edge of the loop.This will highlight the loop and let you inspect it in order to make sure that it is uniquely closed.

You can modify the blade geometry using any of the standard DesignModeler geometry features. Someexamples of the latter are:

• Adding edge blends to the blade geometry

• Trimming the blade and/or hub bodies

• Adding extrusions

Using and Exporting Blades

Once the model is ready in DesignModeler, you can quickly analyze it in the Mechanical application.BladeEditor can also construct a solid model of the periodic flow passage that can be used to perform aCFD analysis of the flow path geometry.

When needed, you can use DesignModeler to export the blade model to the Parasolid, IGES, or STEP fileformat to bring it into your native CAD system.

You can also use BladeEditor to export the blade model for use in ANSYS TurboGrid or Vista TF.



Using and Exporting Blades

The following topics are discussed:Export to Vista TF (.geo)Export as Meanline Data (.rtzt file)Export to ANSYS TurboGrid

Export to Vista TF (.geo)

Similar to the ExportPoints feature, the VistaTFExport feature is used to define the parameters necessary towrite the flow path geometry data (.geo file) for Vista TF. The .geo file contains a 2D mesh of the flow pathgeometry, including the locations of the blade leading and trailing edges. The .geo data also includes theblade type, blade camber surface data, blade thickness data and blade count for each blade row.

If the ThroatArea feature (see Throat Area Feature (p. 39)) is used for a selected Blade, the throat informationfor that blade will be written to the .geo file. This information may improve the calculation of the chokemass flow rate in the Vista TF solver. Without this information, Vista TF will make its own estimate of thethroat area.

The feature properties are listed below.

Table 4 Details View for Meanline Export


[Feature Name]Export Points

[Blade feature selection]Blade(s)

[Yes | No]Export to file

[.geo filename](If Export to file =Yes)

Geo File Name

[Integer Value > 2]Streamwise MeshCount

[Integer Value > 1]Spanwise MeshCount

Selected Blades: [number]a

[Blade reference]Blade 1



aBlade items are listed for all selected blades.

Note

The Vista TF solver expects the flow path (from inlet to outlet) to be oriented in the direction ofthe machine axis, which is the Z-axis.

The VistaTFExport feature requires you to select the Blade features that will be exported to the .geo file. Theselected blades must all belong to the same flow path. Therefore, the VistaTFExport feature can only exportthe data for a single flow path. Only the selected blades in the flow path will be considered for export; allother blades in the flow path will be ignored.


ANSYS BladeEditor

The ‘Export to file’ option specifies whether to explicitly save the data to a .geo file. When using the ANSYSWorkbench project schematic, exporting to a file is unnecessary because the data is transferred automatically.If the .geo file is explicitly written, then you need to specify the .geo file name.

The .geo file contains the geometry coordinates for the flow path in terms of quasi-orthogonal (q-o) ‘lines’running from hub to shroud. The q-o lines are spaced approximately uniformly from inlet to outlet, basedon the mid-span meridional length. The number of q-o lines is specified by the ‘Streamwise Mesh Count’property, where the minimum count is determined based on the number of selected blades in the flowpath. If the specified Streamwise Mesh Count is less than the calculated minimum, then the calculatedminimum will be used.

The number of q-o lines has a direct impact on the throughflow calculation accuracy and computation time.Increasing the number can improve accuracy, but it will also increase computation time. Increasing thenumber beyond a certain maximum may cause instabilities in the convergence process. Typical radial impellerswith an axial inducer should be calculated with around 15 q-o lines in the bladed region, which equates toapproximately a q-o line every 5° of curvature.

The Spanwise Mesh Count property specifies the number of points used to define each quasi-orthogonalline; the points are uniformly spaced from hub to shroud. The minimum number is two. Increasing thisparameter will improve the exported geometry representation for highly curved blades, but it should notbe necessary to go beyond about 30. This parameter has no effect on the number of streamlines that areactually used in the throughflow calculation.

When the .geo file is generated, a warning will be given for the VistaTFExport feature if the streamwise tospanwise aspect ratio of any of the mesh elements is greater than 15 or less than 1/15. Depending on theaspect ratio, you will be suggested to increase or decrease the appropriate streamwise or spanwise meshcount.

Export as Meanline Data (.rtzt file)

To export meanline data, click the Add export points feature icon and set Export Type to Meanline .

The meanline data gives the camberline/thickness definitions on each output layer in an rtzt format (r, theta,z, normal thickness.) Meanline data is exported based on the camber surface and thickness surface datarepresented internally. Therefore, this data may not be representative of the blade if solid model operationshave been made to the blade geometry.

An ExportPoints (Meanline) feature defines the point output for exactly one blade row. A multi-blade rowmodel would require multiple ExportPoints features to output data for more than one blade row. All blades(the main blade and all existing splitter blades) in a single blade row are exported by a single ExportPointsfeature. Regardless of whether you select a main blade or a splitter blade when defining the Blade parameterof an ExportPoints feature, the Blade parameter will always display the main blade. If you suppress any bladein a blade row, the ExportPoints feature for that blade row will also be suppressed.

The feature properties are listed below:

Table 5 Details View for Meanline Export



[Meanline | TurboGrid]Export Type

[Blade feature selection]Blade



Export as Meanline Data (.rtzt file)

[Uniform in M | Uniform in camber-line length]

Point Distribution

[Value>1]Number of Points

Output Layers:a

[Yes | No]Output Layer 1?



aLayer items are listed for all layers defined in the Flow Path.

For the Meanline export type, all blades in the selected blade row are exported. The ‘Number of Points’property specifies how many points are exported from the leading edge to the trailing edge for each blade.The number of points upstream and downstream of the blade(s) is determined by the length tolerance andthe shape of the flow path contours.

The Blade selection lets you select the Blade feature of interest. However, all blades in a blade row are ex-ported.

Export to ANSYS TurboGrid

To transfer blade geometry data to the Turbo Mesh cell of a TurboGrid system, you need to link the Geometrycell to the Turbo Mesh cell and create an ExportPoints feature in BladeEditor to specify which blade geometryshould be exported. The ANSYS TurboGrid export type provides the blade profile data in a format suitablefor defining the blade geometry in ANSYS TurboGrid.

To create the ExportPoints feature, click the icon and set Export Type to TurboGrid . Youmust then select the Blade feature or FlowPath feature and select the surfaces of the blade from which toextract the blade profile data. The blade profile (point) data is automatically extracted from the blade solidmodel at the specified output layers.

Note

Care must be taken to ensure that sufficient output layers are used when exporting so that theANSYS TurboGrid blade surface is a reasonable approximation of the BladeEditor solid model.Note that using many output layers with a small point tolerance can cause Bspline surface loftingproblems in ANSYS TurboGrid. In these cases, you may need to override the Blade GeometricRepresentation in ANSYS TurboGrid and change the Curve and Surface Types to 'Piece-wise linear'and 'Ruled', respectively.

You will need to use one ExportPoints feature for each blade that you wish to export, even if they are inthe same blade row. For example, if you have a main blade and a splitter, you will need to create two Ex-portPoints features and select the appropriate blade surfaces for each feature.

You specify which exported blade(s) to load into ANSYS TurboGrid by editing the Turbo Mesh cell properties.See Table 1: TurboGrid Turbo Mesh Cell Properties (p. 53) for more information.

Because the blade profile data is extracted from the blade surfaces, this feature can also be used to extractblade profile data from an imported CAD model. The only requirement is that a FlowPath feature must bedefined to specify the output layers. If you specify a FlowPath as the Base Feature property, you will needto specify the number of blades and the blade row number. The blade row number lets TurboGrid know


ANSYS BladeEditor

how the exported blades are ordered, and whether any exported blades are part of the same blade row.The blade rows are sorted in ascending order from inlet to outlet.

The blade profile data can also be exported to a file for use by an external application by setting the 'Exportto file' property to 'Yes'.

The feature properties are listed below:

Table 6 Details View for Export to ANSYS TurboGrid



[Meanline | TurboGrid]Export Type

[Yes | No]Export to file

[Folder name](If Export to file =Yes)

File Folder

[Filename prefix](If Export to file =Yes)

File Prefix

[FlowPath or Blade feature selec-tion]

Base Feature


[Named Selection for blade sur-faces]

Blade Surfaces

[Blade feature | User Specified]Blade Info from

[Value>1](if User Specified)

Number of Blades

[Int Value](if User Specified)

Blade Row Num-ber

[0<Value<100]Hub/Shroud Offset%

[Value>1]Point Tolerance

Output Layers:a




aLayer items are listed for all layers defined in the Flow Path.



Export to ANSYS TurboGrid

Configuring the BladeModeler License

BladeModeler requires an ANSYS license to use, although BladeGen will run in "demonstration" mode withoutthe license (no saving or exporting is possible in this mode). Without the license the BladeGen system doesnot appear in the Toolbox, and the only way to access BladeGen is to open a previously saved project thatcontains a BladeGen system. Please contact your ANSYS representative to obtain a license for BladeModelerif you do not already have one.

One BladeModeler license will permit a single user to have BladeGen, DesignModeler, and BladeEditor runningtogether in the same ANSYS Workbench session. This license sharing ability means that no additionalDesignModeler license will be required to use the full functionality of BladeModeler.

In order to use BladeEditor, you must set the Geometry license preference to ANSYS BladeModeler as follows:

1. In the ANSYS Workbench menu, select Tools > License Preferences.

2. In the License Preferences dialog box, click the Geometry tab.

3. If ANSYS BladeModeler is not the first license listed, then select it and click Move up as required tomove it to the top of the list. Furthermore, you should select ANSYS DesignModeler in the list andset its value to 0 (which means “Don't Use”). This prevents DesignModeler from using an ANSYS

DesignModeler license when an ANSYS BladeModeler license is not available.

If ANSYS BladeModeler is not in the list then you need to obtain an ANSYS BladeModeler license.

4. Click OK to close the dialog box.

Click the Help button in the License Preferences dialog box for more information.


ANSYS BladeEditor

Note

IMPORTANT WARNING FOR USERS THAT HAVE AN ANSYS DESIGNMODELER LICENSE

A BladeEditor model will be destroyed if it is modified by DesignModeler under the ANSYS

DesignModeler license. If your project involves a BladeEditor model, then you must ensure thatDesignModeler operates under the ANSYS BladeModeler license (in which case DesignModeleris considered to be running as BladeEditor). Instructions for setting the license preferences appro-priately are given above.

With DesignModeler running under the ANSYS DesignModeler license, it is very important thatyou do not trigger the processing of any Geometry cell that represents a BladeEditor model; inthis case, processing the Geometry cell would cause the associated geometry file to be overwrittenwith a corrupt version. Such processing can occur by updating all or part of the project, or byediting the Geometry cell then making changes in DesignModeler then closing DesignModeler.

If you do edit a Geometry cell that contains a BladeEditor model, and you are using DesignModelerunder the ANSYS DesignModeler license, then DesignModeler will display question marks besidesome of the features listed in the tree view; these are the features that are not recognized byDesignModeler because they are intended for BladeEditor. In this case avoid saving fromDesignModeler, then:

1. Either exit ANSYS Workbench or click File > New to start a new project.

2. Do not save the project when you are presented with a dialog box.

3. Configure your license preferences as specified above.

4. Reopen the project. The old (uncorrupted) files will be restored.



Configuring the BladeModeler License

ANSYS TurboGrid

ANSYS TurboGrid is a meshing tool that is specialized for CFD analyses of turbomachinery bladerows. TheANSYS TurboGrid documentation is available from the Help menu in ANSYS TurboGrid.

The main documentation is available from the Help menu in ANSYS TurboGrid, and consists of the followingparts:

• ANSYS TurboGrid Introduction

• ANSYS TurboGrid Tutorials

• ANSYS TurboGrid User's Guide

• ANSYS TurboGrid Reference Guide

To launch ANSYS TurboGrid from ANSYS Workbench, add the TurboGrid component system to your projectschematic, then edit the Turbo Mesh cell of that system.

The geometry can be loaded from the File menu in ANSYS TurboGrid, or it can be specified by linking aGeometry or Blade Design cell upstream of the Turbo Mesh cell.

In the case when data is transferred to a Turbo Mesh cell from a Geometry cell, the Turbo Mesh cell hasproperties that control this transfer. These are described in Table 1: TurboGrid Turbo Mesh Cell Properties (p. 53).Before attempting to modify these properties, be sure to refresh the Turbo Mesh cell if it is in a Refresh Re-quired state. Refreshing this cell causes the properties to be updated.

Table 1 TurboGrid Turbo Mesh Cell Properties


This property displays a list of theavailable flow paths and bladerows. Use

Flowpath OptionsGeometry Selec-tion

this information as a guide when specify-ing the Flowpath and Bladerow proper-ties (described below). Use the Refreshcommand in the context menu to up-date the list after linking.

This property specifies which Flowpathfeature in BladeEditor contains the

Flowpath

bladerow that is to be loaded in ANSYSTurboGrid.

This property specifies which bladerow(within the specified Flowpath feature)is to be loaded in ANSYS TurboGrid.

Bladerow Number

This property specifies how the inletpoints are positioned in TurboGrid. The

Inlet PositionMethod

Manual option means the user will spe-cify these in TurboGrid. The Adjacent




Blade option means the inlet points willbe calculated using the upstreambladerow, specified below. Only avail-able when multiple bladerows havebeen specified in BladeEditor.

This property specifies the bladerownumber for the bladerow that is imme-

UpstreamBladerow Number

diately upstream of the currentbladerow.

This property is available only when In-let Position Method is set to AdjacentBlade.

This property specifies how the outletpoints are positioned in TurboGrid. The

Outlet PositionMethod

Manual option means the user will spe-cify these in TurboGrid. The AdjacentBlade option means the outlet pointswill be calculated using the downstreambladerow, specified below. Only avail-able when multiple bladerows havebeen specified in BladeEditor.

This property specifies the bladerownumber for the bladerow that is imme-

DownstreamBladerow Number

diately downstream of the currentbladerow.

This property is available only when theOutlet Position Method is set to Adja-cent Blade.

Each ExportPoints feature in BladeEditor defines a single blade, is associated with a FlowPath, and has aBladerow Number. To model a series of consecutive bladerows in a turbomachine, you should define a seriesof ExportPoints features associated with the same FlowPath feature, with Bladerow Numbers in numericalorder (lowest number at the inlet end of the machine). By using the same FlowPath number:

• You have access to the Turbo Mesh cell properties that collectively control the position of the inlet andoutlet ends of each bladerow: Inlet Position Method, Upstream Bladerow Number, Outlet PositionMethod, Downstream Bladerow Number.

• The machine is eligible to be analyzed by Vista TF. For help on Vista TF, see Vista TF User's Guide (p. 61).

If you want a given bladerow to contain more than one blade geometry (for example, main blades withsplitter blades), create one ExportPoints feature for each unique blade in the bladerow, with each ExportPointsfeature based on the same FlowPath and given the same Bladerow Number. When more than one ExportPointsfeature matches the FlowPath and Bladerow Number criteria set in the Turbo Mesh cell properties, ANSYSTurboGrid will create a bladerow with splitter blades.

You can access a context menu for the Turbo Mesh cell in the TurboGrid component system by right-clickingthe cell. Most of the commands that are available are standard, and are described in Systems and Cells. The


ANSYS TurboGrid

only context menu command that is specific to the Turbo Mesh cell is the Edit command, which opens ANSYSTurboGrid.



ANSYS TurboGrid

ANSYS CFX-Pre

ANSYS CFX-Pre is a general-purpose CFD preprocessor that has a turbomachinery setup wizard for facilitatingthe setup of turbomachinery CFD simulations. The ANSYS CFX-Pre documentation is available from the Helpmenu in CFX-Pre.

The documentation is named “ANSYS CFX-Pre User's Guide”.



ANSYS CFD-Post

ANSYS CFD-Post is a general-purpose CFD postprocessor that has features for facilitating the post-processingof turbomachinery CFD simulations. The ANSYS CFD-Post documentation is available from the Help menuin CFD-Post.

The documentation is named “ANSYS CFD-Post User's Guide”.



Vista TF

The Vista TF program is a streamline curvature throughflow program for the analysis of any type of turboma-chine, but has been developed in the first instance primarily as a tool for radial turbomachinery analysis.The program enables you to rapidly evaluate radial blade rows (pumps, compressors and turbines) at theearly stages of the design.

Vista TF is provided by PCA Engineers Limited, Lincoln, England.

The documentation for Vista TF is provided in the following sections:Vista TF User's GuideVista TF Reference Guide

Vista TF User's Guide


Vista TF is operated from ANSYS Workbench by working with the Vista TF component system. The latter iscomprised of three cells: a Setup cell, a Solution cell, and a Results cell:

The name of the Vista TF system is changeable upon first adding the system, or by right-clicking the bluecell and selecting Rename, then typing in a new name. Note that the name of the system appears belowthe system.

Vista TF uses the following input to define a run:

• A geometry (*.geo) file

• Setup cell properties

• Three Vista TF template files

– a control data file (*.cont)

– an aerodynamic data file (*.aert)

– a correlations data file (*.cort)

The general procedure for running a simulation in Vista TF is:



1. Drag the Vista TF component system from the Toolbox to the Project Schematic, or double-click thesystem in the Toolbox.

2. Specify a geometry file using either one of the following methods:

• Connect an upstream Geometry cell that contains a VistaTFExport feature to the Setup cell.

If there is more than one VistaTFExport feature, then the first valid and unsuppressed one is used.

• Right-click the Setup cell, select Import Geometry, and browse to select a geometry (*.geo) file.

3. Double-click the Setup cell, then configure the Setup cell properties.

For details, see Vista TF Setup Cell Properties (p. 62).

4. Optionally customize one or more of the three template files (*.cont, *.aert, *.cort).

For details on customizing the template files, see Customizing the Vista TF Template Files (p. 66).

5. Update the Solution cell, or update the Project, to generate a solution.

6. Double-click the Solution cell to view the solver output.

7. Double-click the Results cell to view the results in CFD-Post.

The Results cell has one property that you can edit to control report generation.

The following topics are discussed:Vista TF Setup Cell PropertiesCustomizing the Vista TF Template FilesVista TF Context Menu Commands

Vista TF Setup Cell Properties

The main properties that control Vista TF are associated with the Setup cell. To see the properties, do anyone of the following:

• Right-click the Setup cell and select Edit.

• Double-click the Setup cell.

• Right-click the Setup cell and select Properties.

A sample of the cell properties is shown in Figure : Properties of the Vista TF Setup Cell (p. 63).


Vista TF

Figure: Properties of the Vista TF Setup Cell

Table 1: Vista TF Setup Cell Properties (p. 63) describes each of the cell properties.

Table 1 Vista TF Setup Cell Properties


The name of the cell with which thepresent set of properties is associated.

Cell IDGeneral

This property appears when there is nocell upstream of the Setup cell.

Machine Type

This property defines the machine type.

The choices are:

• Pump





• Axial Compressor

• Centrifugal Compressor

• Fan

• Axial Turbine

• Radial Turbine

• Hydraulic Turbine

• Other

• Unknown

This property specifies which templatefiles are used and which report is usedfor the results. You can customize thesetemplates. For details, see Customizing

the Vista TF Template Files (p. 66).

This property appears when there is nocell upstream of the Setup cell.

Number of BladeRows

This property defines the number ofblade rows in the geometry (.geo) file.

This property defines the number ofmeridional streamlines to use in the

Number ofStreamlines

Solver Settings

calculation. For details, see Specification

of the Control Data File (*.con) (p. 74).

This property defines the maximumnumber of solver iterations. For details,

Maximum Itera-tions

see Specification of the Control Data File

(*.con) (p. 74).

This property defines the direction ofrotation of the blades about the Z axis.

Machine Rotation-al Direction

Operating Condi-tions

The choices are:

• Right-handed

• Left-handed

This property defines the rotationalspeed of the machine.

Machine Rotation-al Speed

This property specifies the types ofboundary conditions.

Flow Option

The choices are:

• Mass Flow

• Pressure Ratio

• Pressure Difference


Vista TF


For details, see Specification of the Con-

trol Data File (*.con) (p. 74) and Specific-

ation of Aerodynamic Data File

(*.aer) (p. 91).

This property defines the outlet-to-inletratio of absolute total pressures (each

Pressure Ratio

(For Flow Option= Pressure Ratio)

pressure measured in the stationaryframe).

This property defines the outlet-to-inletdifference of total pressures (each pres-sure measured in the stationary frame).

Pressure Differ-ence

(For Flow Option= Pressure Differ-ence)

This property defines the inlet mass flowrate.

Mass Flow Rate

This property defines the inlet absolutetotal pressure (measured in the station-ary frame).

Inlet Total Pres-sure

This property defines the inlet absolutetotal temperature (measured in the sta-tionary frame).

Inlet Total Temper-ature

This property defines the angle of theinlet velocity measured with respect to

Inlet Swirl Angle

the meridional plane. A positive angleimplies that the flow swirls in the Ma-chine Rotational Direction.

This property defines the reference dia-meter for all blade rows. For details, see

Reference Diamet-er

Reference Values

Specification of Aerodynamic Data File

(*.aer) (p. 91).

This property defines the small-scalepolytropic efficiency for the machine.

Polytropic Effi-ciency

This property defines the type of fluidthat flows through the machine.

Fluid OptionFluid Properties

The choices for this property are:

• Ideal Gas

• Liquid

This property defines the specific heatcapacity (at constant pressure) of theideal gas.

Gas Specific HeatCp

(For Fluid Option= Ideal Gas)

This property defines the specific heatratio of the ideal gas.

Specific Heat Ratio





(For Fluid Option= Ideal Gas)

This property defines the density of theliquid.

Fluid Density

(For Fluid Option= Liquid)

This property defines the specific heatcapacity of the liquid.

Fluid Specific Heat

(For Fluid Option= Liquid)

This property indicates the dynamicviscosity of the fluid as follows:

Dynamic Viscosity

• A value less than 1 [N s m^-2] (orequivalent value in other units) isinterpreted as the dynamic viscosity.Note that the value must be greaterthan 0.0000001 [N s m^-2].

• A value of 0 causes Vista TF to calcu-late the dynamic viscosity from aninbuilt equation for dynamic viscos-ity based on Sutherland’s law andthe Inlet Total Temperature. Thisworks only for an ideal gas.

• A value greater than 1 [N s m^-2](or equivalent value in other units)is interpreted as the Reynolds num-ber, in which case Vista TF calculatesthe dynamic viscosity using thisReynolds number, the ReferenceDiameter, the Machine RotationalSpeed, and the fluid density.

This property serves as an initial guessfor the meridional velocity divided by a

Initial Cm/U_refInitial Conditions

characteristic velocity, where the latteris half the Reference Diameter multi-plied by the Machine Rotational Speed.For more information, see the descrip-tion for cm_start in Specification of

the Control Data File (*.con) (p. 74).

Customizing the Vista TF Template Files

When you run Vista TF, one of each of the *.cont, *.aert, and *.cort data files are copied from the Vista TFtemplate directory into your working directory as required (that is, if they are not already present in theworking directory). The exact *.cont, *.aert, and *.cort files that are copied (and then used during a run) dependon the Machine Type setting in the Setup cell properties. You can use custom versions of any of the *.cont,*.aert, and *.cort files. To customize one of these files:


Vista TF

1. Import the template you want to customize by right-clicking the Setup cell and selecting one of theImport Template commands.

The selected template file is copied to the working directory. If you import the same template filemore than once, the name of the copied file is changed automatically to produce a unique file name;the last one imported will take effect when you start a run.

2. From the Workbench main menu, select View > Files to see the template files you have imported.

3. Right-click the template file that you want to customize, and select Open Containing Folder.

4. Open the template file in a text editor and change it.

In these files, do not change setting values that are between a pair of braces (“{” and “}”). You canchange setting values which are not wrapped in braces.

The settings of the template files correspond with the settings of the *.con, *.aer, and *.cor files whichare described in Specification of the Control Data File (*.con) (p. 74), Specification of Aerodynamic Data

File (*.aer) (p. 91), and Specification of Correlations Data File (*.cor) (p. 101).

Vista TF Context Menu Commands

You can access a context menu for each cell in the Vista TF component system by right-clicking a cell in thesystem. Most of the commands that are available are standard, and are described in Systems and Cells. Thecontext menu commands that are specific to the Vista TF system cells are described in Table 2: Context Menu

Commands Specific to the Vista TF System Cells (p. 67).

Table 2 Context Menu Commands Specific to the Vista TF System Cells

DescriptionCommandCell

This command opens the VistaTF properties view.

EditSetup

This command enables you tospecify the geometry file,

Import Geometry

provided that there is no up-stream Geometry cell linkedto the Setup cell.

This command enables you toimport a template file. For de-

Import Template

tails, see Customizing the Vista

TF Template Files (p. 66).

This command opens the VistaTF screen output (.scn file) for

View Solver OutputSolution

viewing. For details, see Screen

Output Files

(screen.scn) (p. 74).

This command restarts thesolver. You can use this com-

Continue Calculation

mand to continue a run thatdid not converge; in this case,the Update command may notwork because the cell isalready up-to-date.



Vista TF Context Menu Commands

DescriptionCommandCell

This command opens the res-ults in CFD-Post.

EditResults

Vista TF Reference Guide


The key aspect of this document is the input and output data specification for the program and how to runit.

The input files include a control file, an aerodynamics file, a geometry file, a correlations file, and can alsoinclude a restart file providing data from a previous converged simulation. The input files include commentlines to help the reader to identify the parameters.

The output files include a results file with text output for analysis of the simulation giving:

• Data on streamlines and quasi-othogonals (short for “quasi-orthogonal calculating stations”)

• Various files with the same information that can be used for plotting the results

• A file which monitors the history of the simulation

• A file to act as interface to other software systems

• A restart file which can be used to initialise a further simulation.

For radial pump and turbomachinery calculations in subsonic flow the program is very robust, but sometips on possible problems with running the program are also provided.

The topics in this guide are:Running Vista TF from the Command LineInput and Output Data Files for Vista TFSoftware LimitationsStreamline Curvature Throughflow TheoryAppendices

Running Vista TF from the Command Line

You can run Vista TF from the command line of your operating system. By default, the executable will lookin the current directory for the required input files for your case. One of the input files, which has a defaultname of vista_tf.fil , contains the names of the other input files that are to be used for the case. Ifthis input file has a different name, specify that name as the first command line argument. For example:

VistaTF.exe myfile.fil

When the executable runs, it writes text output messages to the console. To redirect these messages to afile, append -silent to the command line. The default file name for storing the redirected output messagesis screen.scn . To store the output messages in a file of a different name, specify that name following-silent .


Vista TF

After running the program, several files are produced in .csv format as the basis for producing plots withCFD-Post or in .txt format as the basis for producing plots with Tecplot.

The input and output files for VistaTF.exe are described in detail in Input and Output Data Files for Vista

TF (p. 69).

Input and Output Data Files for Vista TF

The following sections describe the input and output files for VistaTF.exe .The Auxiliary File with the Default Name: vista_tf.filOverview of Input FilesOverview of Output FilesSpecification of the Control Data File (*.con)Specification of the Geometry Data File (*.geo)Specification of Aerodynamic Data File (*.aer)Specification of Correlations Data File (*.cor)Specification of the Output Data File (*.out)Specification of the Text Data Files (*.txt)Specification of the CFD-Post Output Files (*.csv)Specification of Convergence History Data File (*.hst)

The Auxiliary File with the Default Name: vista_tf.fil

You specify the input data and output data file names in an auxiliary data file which has the default filenamevista_tf.fil . This file can have another name if this name is passed to the program through a command-line argument to specify the auxiliary filename, as described in Running Vista TF from the Command Line (p. 68).If no command-line argument is specified in this way, then the program assumes that the file has the namevista_tf.fil . This auxiliary file in turn must contain the necessary filenames for the input and outputfiles in the following order and form:

control datafile name prefix.congeometry datafile name prefix.geoaerodynamic datafile name prefix.aercorrelation datafile name prefix.corresults output file name prefix.outconvergence history filename prefix.hsttext data output file name prefix.txtCfx-post output file name prefix.csvrestart datafile name prefix.rstInterface output file prefix.int

Note that the prefixes need not be identical for a given run. In fact this is not usually the case. An exampleof a vista_tf.fil file is:

standard_control.conimpeller_XYZa.geodesign_point.aerradial_impeller.corresults.outhistory.hstimpeller.txtcfx_post.csvrestart.rststream.int

Note that the program also produces and uses other files in special situations as outlined below; their namesdo not need to be specified separately because they are determined by the program. The data files, resultsfiles, and the file vista_tf.fil should be in the same directory. If the history (.hst ) file already exists



Input and Output Data Files for Vista TF

in the working directory before the program is run, it will be overwritten. If the restart (.rst ) file alreadyexists in the working directory before the program is run, it will be overwritten only if the solution hasconverged or reached the maximum number of iterations that you have specified. If the output (.out ) fileand the plot files (.txt , and .csv ) already exist in the working directory before the program is run, theywill be overwritten. The program will not prompt you for permission to overwrite these files.

Overview of Input Files

Four input data files are always needed:

Control data file (.con)Geometrical data file (.geo)Aerodynamic data file (.aer)Correlations data file (.cor)

A fifth input file will be used if it is available and if you specify that it should be used:

Restart data file (.rst)

The division of the input data into separate files provides a simple and clear way to vary or retain the annulusgeometry, the aerodynamic conditions, the blade element data, or the correlations being used, withoutchanging all the files in use. Typically during the design process, you will change the .geo file to examinea new geometry, and the .aer file to examine new operating points or boundary conditions, and you willleave the .con and .cor files untouched once you have configured their settings to meet the requirements.

The data specified in the individual files is structured to be as logical as possible, but some small overlapbetween the different files is inevitably necessary. The structure may appear more complicated than necessary,but this arises from the requirement that ultimately the program should calculate all types of turbomachineryin single stage and multistage configurations, both as ductflow and as throughflow calculations. During thedevelopment an attempt has been made to include a built-in “expert system” in the program. For example,the program itself is able to identify whether a particular blade row is a radial compressor impeller or a ra-dial turbine inlet guide vane (from the geometry) and ultimately will be able to select automatically themost appropriate correlations to be used. In general many parameters may be set to zero and the programselects the value it deems appropriate. “Expert parameters” allow you to override the selections that theprogram would automatically make.

The functions of the five input data files are summarized next:

Control Data File (.con)

This is a short file giving values of identifiers of the file (title and headers) and control information andconstants defining such choices as the number of streamline calculating planes, the convergence tolerance,the relaxation factors, and so on. Various “expert” parameters are also specified in this file. Also specified inthis file are the planes and stations for which output information is required, and the level of detail requestedon these planes.

To make the program easier to use, you can specify many of these parameters as 0.0, 1.0, or 0, and theprogram will then make a sensible choice of the value for the parameter concerned, so that typically youare only concerned with two or three parameters in this file. The control parameters that determine the se-lection of particular numerical models are also defined in this file, for example the type of span-wise mixingor the model for blade row choking. In general, this input file does not need to be changed from run to run.

Geometry Data File (.geo)

The geometry data file contains the dimensions of the annulus in terms of the axial and radial coordinatesof the quasi-orthogonal calculating planes at hub and casing, and information to identify the type of calcu-


Vista TF

lating station (such as duct, stator, or rotor). Calculating planes can represent regions of a duct or blades(leading edges, trailing edges, and internal stations) and can be curved or linear. For linear calculating planes(which, by definition, are straight in the meridional plane), details of the geometry of each calculating planeare specified at only two points and intermediate geometric values are interpolated linearly from these,whereas curved planes require more points to be specified across the span. For curved duct calculatingplanes, this geometry data specifies the co-ordinate points along the curved calculating plane. In blade regions,the coordinates of the calculating plane, together with information about the blade geometry at this location,must be specified (including the number of blades, blade lean angles, and blade thickness). For each bladerow, additional geometrical parameters can be specified that might be relevant for the correlations (suchas the throat area, the location of the throat, the location of maximum camber, the maximum thickness, thetrailing edge thickness, and the tip clearance).

In general, the geometry data file will be generated automatically using a blade geometry definition program(such as ANSYS BladeEditor, or Vista GEO of PCA). A geometry conversion program is available to convertdata from the BladeGen meanline RTZT output format into the .geo file format for the throughflow programand this has been tested for radial impeller rotors and stators, and axial stator and rotor blade rows (com-pressors and turbines); see Appendix G: The RTZTtoGEO Program (p. 147). Other custom tools are available forconversion of geometrical data from specific formats into the Vista TF .geo file format, and others can beprepared as required.

Aerodynamic Data File (.aer)

The aerodynamic data file contains the definition of the fluid, boundary conditions, and operating data suchas inlet conditions and rotational speed. It includes parameters related to aerodynamic models for the meanstream surface description, and the spanwise mixing coefficient.

Correlation Data File (.cor)

The correlation data file provides details of control parameters and empirical constants and data for theparticular choice of empiricism that has been chosen. The method allows a general specification of losses,flow angle, and blockage for all calculating planes and across the span through the definition of the spanwisevariation of these parameters at particular quasi-orthogonal locations and for particular blade rows. Ultimately,in many cases, if default values of zero are chosen for these parameters then the program should automat-ically select appropriate correlations and make its own choice of correlation parameters.

Restart Data File (.rst)

This restart file contains some key information from a previous calculation in a non-dimensional form. Notethat the restart file can be for different flow conditions and for a different geometry but it must have thesame number of quasi-orthogonal calculating stations and streamlines as the current calculation. If the restartdata file has been generated from a calculation with similar geometry and flow conditions as the currentcalculation, it provides a much better initial estimate of the flow and the streamline positions than the firstestimate generated internally within the program, promoting more rapid convergence. A restart with un-changed conditions and geometry will generally have a meridional velocity error of less than 2% and willconverge almost immediately, except for choked flows where more iterations are needed. Convergence withthe restart file is never immediate, even with unchanged geometry and flow conditions, because not all ofthe solution is saved to the restart file, and so some data needs to be regenerated over a few iterations ofthe solution. For small changes in flow conditions or geometry, the number of iterations when using therestart file is generally less than 50% of that required when starting from the program's own first estimate.

An existing restart file cannot be used if the number of streamlines or quasi-orthogonals is changed. Theprogram recognizes if the number of streamlines or quasi-orthogonals has been changed and makes a newcold start in this case.




You do not have to be concerned with the content and format of the restart file because it is generatedautomatically at the end of a run of the program, and is automatically used if it is available. No further in-formation is provided here with regards to the content of the restart file. In some situations where it is difficultto obtain convergence, the restart file can be used to store results for a converged operating point (at lowerspeed, for example) and then the required operating condition can be obtained by starting from the restartfile with new flow conditions. In other cases where an un-converged solution has been stored in the restartfile, it is possible that using the restart file can be disadvantageous as a starting point for a new simulation,and a cold-start may be better.

The restart file can also be used for reducing the number of computations when the program is coupled toan optimizer. In this case, an additional restart file with the name best_restart.rst is used and generated.

Overview of Output Files

The program always creates the following three output files:

• Results output file (.out )

• Convergence history file (.hst )

• Restart data file (.rst )

In addition, the program can create the following output files of tabular data for plot and display purposes,depending on the value of the parameter i_display in the control file:

• Several comma separated variable output files for CFD-Post (.csv )

• Several text output files in a format suitable for Tecplot (.txt )

There is one CFD-Post output file for a calculation with no blade rows and four additional files for each bladerow. There are two Tecplot output files for a calculation with no blade rows, and an additional file for eachblade row.

In addition, the program can create a data file containing data in a specific format for use with other programs:

• Interface output file (.int )

and a file which can be produced as an alternative to the screen output:

• Screen output file (screen.txt )

Results Output File (.out)

This contains rudimentary details of the data used for the calculation and the results of the calculation atevery plane and radial station for which output has been requested. An overview of the content of this fileis given in Specification of the Output Data File (*.out) (p. 111).

Convergence History File (.hst)

This contains a recording of the input data, followed by details of the convergence of the main iterativeprocedures, and extensive details of the terms in the radial equilibrium equation for each stream tube andcalculating plane. It is rare for this to be examined in any depth, but this can be useful to identify problemsif the solution fails to converge.


Vista TF


This restart file stores information from a converged calculation in a non-dimensional form. It provides amuch better initial estimate of the flow and the streamline positions than the first estimate generated internallywithin the program. It reduces the calculation time for a calculation with slightly modified geometry orchanged aerodynamic data by more than 25%. If an existing restart file is available, it will be overwritten bythe program.

Comma Separated Variable Output Files for CFD-Post (.csv)

Depending on the value of i_display in the control file, the following files are produced:

• prefix.csv

• global_prefix.csv

together with four additional files produced for each blade row from 1 to n:

• row_0n_hub_prefix.csv

• row_0n_mean_prefix.csv

• row_0n_tip_prefix.csv

• row_0n_loading_prefix.csv

The first file (prefix.csv ) contains key results of the calculation at every calculating plane and streamlinein a form that can be used for setting up a meridional contour plot of the results. The second contains asummary of the global performance and reference parameters for the calculation. The additional four .csvfiles are produced for each blade row in the calculation. These contain the same information as in the rowdata from the .txt files, but separated into hub, mean, and tip streamline data, which is information alongthe blade calculating station from leading to trailing edge on the hub, mean, and tip streamlines. The addi-tional file contains spanwise variation of data. This can be used to define typical blade loading diagramsand incidence plots for each blade row.

Even if no .csv file is required, the prefix.csv file still needs to be specified in the vista_tf.filfile.

Text Data Output Files for Tecplot (.txt)

Depending on the value of I_display in the control file, the following files are produced:

• prefix.txt

• test_prefix.txt

Together with one additional file produced for each blade row from 1 to n:

• row_0n_prefix.txt

The first file (prefix.txt ) contains key results of the calculation at every calculating plane and streamlinein a form that can be used for setting up a meridional contour plot of the results, using Tecplot software.This is an ASCII file which is formally correct for presenting the results in graphical form with the plot pro-cessing software Tecplot, but can be used by other plot systems (such as Excel) with appropriate conversionor macros. A standard layout file for Tecplot (flowfield_2d.lay ) has been prepared for typical meridi-onal plots from Vista TF calculations. There are no macros included in this so this may need some adjustmentfor a typical case (scale of axes, level of contour values, and so on). The second text file (test_prefix.txt )



Text Data Output Files for Tecplot (.txt)

contains the grid of the initial estimate of the streamlines and quasi-orthognals. This can be useful for de-bugging purposes and can be used to plot the initial grid of an un-converged calculation to identify anyspecific problems with this. The additional .txt files are produced for each blade row in the calculation(row_0n_prefix.txt where n is the number of the blade row from the inlet). These can be used todefine typical blade loading diagrams and incidence plots for each blade row. The Layout files for Tecplotthat have been prepared in advance assume that the .txt file has the prefix “impeller ”.

Even if no .txt file is required, the prefix.txt file still must be specified in the vista_tf.fil file.

Interface Output Files (.int)

If you request the generation of an interface file for another analysis program then the appropriate files arealso generated. The first use of this has been established to allow a summary of the results to be obtainedas input to an optimizing software system. A second option will be to generate the .stream file for MISESblade-to-blade calculations providing the streamtube thickness and the radius along a stream section. Evenif no interface file is required, the .int file still must be specified in the vista_tf.fil file.

Screen Output Files (screen.scn)

In normal operation, the progress of the program can be seen on the screen. If the command line includesa parameter -silent , the screen results will be written to a separate file called screen.scn and not tothe screen. If this parameter is not present, this output goes to the screen. If a name follows this parameter,the screen results are printed to a file with this name.

Specification of the Control Data File (*.con)

The control data file includes sections of text that help you to identify the parameters defined here. Notethat if values are set to 0.0 or 0 then standard values are used, so typically you do not have to worry aboutthis input. If zero values are specified for some parameters then the values actually selected by the programare written to the output file. Standard forms of this file are available for editing to meet the specific require-ments, whereby in most cases no modification of the file is necessary. An example of a control data file isgiven in Appendix B: Example of a Control Data File (*.con) (p. 130).

Section 1: Character strings identifying the control data (max 72 characters/line)The syntax is:

Character string - title(1)Character string - title(2)Character string - title(3)

Section 2: Integer control parametersThe syntax is:

n_sl max_it_main max_it_mass

DescriptionParameter

Number of meridional streamlinesn_sl

Notes:

• Must be an odd number so that there is always a midstreamline.

• Typically n = 9 or 17. If n_sl = 0, then 9 will be used.

• Maximum n_sl = max_n_sl = 19.


Vista TF


• If the mixing model is being used, (i_mix > 0 in section4) then there has to be a minimum of 9 streamlines.

Maximum number of iterations of the main streamlinecurvature loop in the iterative method.

max_it_main

Notes:

• Typically specified as 500 but fewer are generally neededfor simple radial compressor calculations to attain conver-gence.

• If max_it_main < 4 then max_it_main = 4, so thatat least 4 iterations are always done as a minimum.

• If max_it_main = 0 then max_it_main = 500.

• If the flow reaches the convergence limit before themaximum number of iterations is reached then the calcu-lation is automatically stopped earlier.

Maximum number of iterations for internal mass flow loopat each quasi-orthogonal calculating station.

max_it_mass

Notes:

• Typically 10 and if max_it_mass = 0, thenmax_it_mass = 10.

• If max_it_mass < 5 then max_it_mass = 5; experienceshows that this is a sensible value.

• If max_it_mass > 20 then max_it_mass = 20.

• If the mass flow convergence tolerance at a particularquasi-orthogonal is reached before the maximum numberof iterations are completed then mass flow iteration isstopped early.

Section 3: Integer control parameters that control input and output dataThe syntax is:

i_print_plane i_print_level i_progress i_display i_restart i_interface

Note that setting all of these parameters to 0 gives a standard form of output.


Determines the quasi-orthogonal calculating planes at whichdata is output into the results file.

i_print_plane

= 0, as i_print_plane = 4

= 1, output at no planes

= 2, data at inlet and outlet planes only





= 3, data at leading edges and trailing edges and inlet andoutlet planes only

= 4, data at all planes

Note:

The extent of the data printed at each plane is determinedby i_print_level .

Determines the level of output data printed into the resultsfile at each output plane.

i_print_level

= 0, standard output (as iprint_level = 3)

= 1, very limited data at each plane

= 2, generous level of data at each plane

= 3, extensive data at each plane

Note:

The planes at which output is available are defined by theparameter i_print_plane .

Determines the extent of intermediate data that is printedto the various files.

i_progress

• If i_progress = 0 then no intermediate information isprinted.

• If i_progress = 1 then intermediate progress of theiterations are printed to the history file.

• If i_progress = 2 then data is printed to the historyfile and to the screen.

Determines extent of tabular data output which is preparedfor displaying the results with other plot and post-processingtools:

i_display

Notes:

• If i_display = 1, then no plot files are produced.

• If i_display = 0 then the output files of type .txt areproduced for display of the results with Tecplot.

• If i_display = 2, then a comma separated variable filewith extension .csv is produced for display of the resultswith CFD-Post.

• If i_display = 3, then both i_display = 0 and 2above are activated.

• Other output formats can be incorporated as requested.

Determines whether the restart file should be used andwhether the results will overwrite the restart file contents.

i_restart


Vista TF


Notes:

• If i_restart = 0, the restart file (prefix.rst ) will beused automatically if it is present (a warm start) and itscontent will be overwritten automatically at the end of anormal calculation. Note that this also overwrites the re-start file even if the iterations are not converged, so thata second start with the same number of iterations startswith a better approximation. This is the normal way touse the program. The restart file includes the number ofquasi-orthogonals and streamlines. If i_restart = 0and this number has changed then the program makesa cold start with its own estimate of inititial conditions(as in i_restart = 1).

• If i_restart = 1 the restart file (prefix.rst ) will notbe used even if it is available and the program will set upits own initial conditions (a cold start). The content of therestart file will be overwritten as under 1 above. This isnot generally recommended but can be useful in debug-ging difficult cases. This is equivalent to deleting the ex-isting restart file and using option 1 above.

• i_restart = 2 and 3 are special options for runningthe program when coupled to an automatic optimizer. Inthese cases the use of a good restart file reduces thenumber of iterations needed and brings a reduction incalculating time. Unfortunately some of the geometriesbeing examined may be poor and so it is inadvisable tooverwrite the restart file with poor results. If i_restart= 2 then the file runs with a restart file called best_re-start.rst and writes the results on to prefix.rst .If i_restart = 3 then the file runs with a restart filecalled best_restart.rst and also writes the resultson to the same file best_restart.rst . In both casesif the restart file best_restart.rst is not presentthen the internal initial estimate is used (a cold start).

Determines the type of output interface file that is generated.i_interface

Notes:

• If i_interface = 0 then no output interface file isgenerated.

• If i_interface = 1 then the prefix.int file containsa summary of the results for use in radial compressoroptimization.

• Other options are in preparation, such as a link to theblade-to-blade program MISES.

Section 4: Integer control parameters for various models and reference parametersThe syntax is:




i_expert i_flow i_fluid i _inbc i_mass i_mix i_ree


Allows special calculations to be carried out making use ofdevelopment features of the program. Normally you would

i_expert

set the value of this parameter to 0 or 1, but other expertfeatures of the program may be modified with this controlparameter. Each digit of the parameter has an influence onits effect.

Notes:

• The last digit controls the choke calculation mode. Usinga value of zero for the last digit causes the choke massflow limitation to be eliminated which may be more ro-bust in difficult cases. Calculations of new cases shouldstart in this mode.

• Using a value of 1 for the last digit, enables the chokemass flow limitation calculation. This requires exact datafor the throat areas to be specified and should only beused if this is available. It is necessary to set this value to1 when using iteration to pressure ratio in choked stages.

• The second-last digit controls the blending function cal-culation for the deviation between the blade angle andthe flow angle as follows:

0 - Turbines use departure angle at the leading and trail-ing edge ends, Compressors use swirl at the leading edgeand departure angle at the trailing edge.

1 - Turbines and compressors use the departure angle forthe leading and trailing edges.

2 - Turbines and compressors use departure angle at thetrailing edge and relative swirl at the leading edge.

3 - Turbines and compressors use departure angle at thetrailing edge and the absolute swirl at the inlet.

4 - Compressors use swirl at the leading edge and depar-ture angle at the trailing edge; turbines use swirl at theoutlet and departure angle at the leading edge.

5 - Compressors use swirl at the leading edge, departureangle at the trailing edge; turbines use swirl at the trailingedge and departure angle at the leading edge.

Determines the input definition for the reference flow para-meters (which are input in .aer file).

i_flow

Notes:

• i_flow = 0 then ref_mach , ref_phi , and ref_d , arespecified, but if ref_mach > 3 then it is interpreted as


Vista TF


ref_u , so this is equivalent to ref_u , ref_phi , andref_d .

• i_flow = 1 then ref_n , ref_mass , and ref_d arespecified.

Note: If there is more than one spool in the calculationwith different rotational speeds, then this is taken intoaccount as follows:

- If i_spool = 2 and i_flow = 1 then ref_n1 ,ref_n2 , ref_mass , and ref_d are specified.

- If i_spool = 3 and i_flow = 1 then ref_n1 ,ref_n2 , ref_n3 , ref_mass , and ref_d are specified.

• i_flow = 2 then ref_n , ref_volume , and ref_d arespecified.

• i_flow = 3 then ref_u , ref_mass , and ref_d arespecified.

• i_flow = 4 then ref_u , ref_volume , and ref_d arespecified

• i_flow = 5 then ref_n , ref_mass , and ref_d arespecified together with the ref_pr (total to static pres-sure ratio between inlet plane and the last trailing edgeon the mid-streamline). The value of ref_mass is a startvalue for mass flow in the iteration to pressure ratio andhas no effect on the final solution.

• i_flow = 6 then ref_n , ref_mass , and ref_d arespecified together with ref_pr (total to static pressureratio) together with n_p_te (the total number of trailingedges at which a guessed value of the static pressure ratiois specified, followed by the guessed pressure ratios ateach trailing edge, including the last, which is also definedby ref_pr .

• i_flow = 7 then ref_n , ref_mass , and ref_d arespecified together with the ref_p (static pressure at thelast trailing edge on the mid-streamline). The value ofref_mass is a start value for mass flow in the iterationto outlet pressure and has no effect on the final solution.This option may be useful for low speed devices wherepressure ratio becomes indeterminate.

• i_flow = 8 then ref_n , ref_mass , and ref_d arespecified together with the ref_p (static pressure attrailing edge pane) together with n_p_te (the totalnumber of trailing edges at which a guessed value of thestatic pressure is specified, followed by the guessedpressures at each trailing edge, including the last, whichis also defined by ref_p .





• i_flow = 9 then ref_n , ref_mass , and ref_d arespecified together with the ref_cu (absolute swirl velo-city at the last trailing edge on the mid-streamline). Thevalue of ref_mass is a start value for mass flow in theiteration to outlet swirl and has no effect on the finalsolution. This option may be useful for turbine calculationswhere the last blade row is a turbine rotor.

• Other options are available for debugging purposes.

• The geometry definition of Vista TF assumes clockwiserotation. This leads to a certain convention for the signof the blade angles (see Appendix A: A Note on Sign Con-

vention for Angles and Velocities (p. 127)). In some casesyou may have a counterclockwise machine with bladeangles of the opposite sign. To avoid the need to changeall the angles specified in the .geo file, an option isprovided whereby the value of i_flow is given a negat-ive sign.

Determines the model for the equation of state of the fluid:i_fluid

• If i_fluid = 0 then ideal gas with constant specific heat.

• If i_fluid = 1 then liquid.

Determines the type of inlet boundary conditions:i_inbc

• i_inbc = 0 then input values are total pressure, totaltemperature and swirl (r x cu , that is radius times circum-ferential component of the absolute velocity) on the inputplane.

• i_in_bc = 1 then input values are total pressure, totaltemperature, and absolute flow angle.

Determines whether the mass flow is uniformly distributedacross streamlines or not.

i_mass

• i_mass = 0 then mass flow between each streamline isthe same.

Determines which mixing model is used:i_mix

• i_mix = 0 then no mixing model.

• i_mix = 1 then a spanwise mixing model based on eddydiffusion across the streamlines will be used. Note thatthis requires a minimum of 9 streamlines (n_sl => 9).

Determines the form of the radial equilibrium equation thatis used to determine the velocity gradient along the quasi-orthogonal.

i_ree

• i_ree = 0 then the equations as given in the paper ofCasey and Roth (1984) are used, except that the dissipa-tion term is set to zero and the blade force term is set tozero at a trailing edge and at a leading edge.


Vista TF


• i_ree = 1 then the solution is as for i_ree = 0 but thedissipation term is not set to zero but the equations asgiven in the theory documentation are used.

• i_ree = 2 then the dissipation term is not set to zerobut the equations given in the paper of Casey and Roth(1984) are used.

• i_ree = 3 then the velocity gradient in the radial equi-librium equation is reduced by the factor grad_reegiven in section 5. This is useful for debugging difficultcases and the simulation becomes similar to a mean-linecalculation with no gradient of meridional velocity acrossthe span. If grad_ree = 1.0 then selecting i_ree = 3has no effect.

Section 5: Convergence and damping factorsThe syntax is:

damp_sc damp_vl cm_start tolerance_cm tolerance_mass grad_ree

The damping factor model automatically chooses the most appropriate values of these parameters basedon the type of machine and the grid. You would typically specify the following values for this section:

0.00 0.00 0.00 0.00 0.00 1.00


Damping factor for streamline curvature terms.damp_sc

Note:

• The Wilkinson stability analysis for streamline curvatureprograms indicates that the streamline curvature dampingterm has to be reduced for long closely spaced quasi-or-thogonals (high aspect ratio). For details, see the sectionon computational grid (Computational Grid (p. 144)).

• If damp_sc = 0.0 then the program determines the valueof damping factor from the theory of Wilkinson, or uses0.25, whichever is smaller.

• Typically values of damp_sc between 0.05 and 0.25 areused, but lower values may be necessary for high aspectratio quasi-orthogonals (as in end stages of steam tur-bines).

• If the specified value of damp_sc is larger than the valuepredicted by the Wilkinson stability theory then the pro-gram automatically reduces the damping factor to a stablevalue.

• If the program has convergence problems with an increas-ing error then the value is automatically reduced internallywithin the program during the convergence process.





• Several different schemes for the damping are applied.The original scheme is obtained with a value of damp_scbetween 1.0 and 1.25. New schemes which are morestable and robust in most cases can be obtained with thevalue of damp_sc between 0.0 and 0.25. A value betweenor 2.0 and 2.25 uses the original scheme with changedconstants. The first digit then defines which scheme isused (0 - original, 1 - modified original, 2 - new scheme)and the digits after the decimal point are the dampingfactor itself.

Damping factor on velocity level. Note this damping factoris also used internally in the program for all parameters whichare under-relaxed.

damp_vl

Notes:

• There is no stability theory to define this, and a typicalvalue used is 0.50, indicating that 50% of the new para-meter together with 50% of its original value is used.

• If damp_vl = 0.0 then 0.50 is used.

Value of meridional velocity on the mean streamline as afraction of u_ref , as used in the initial conditions. This is

cm_start

then a sort of flow coefficient (cx /u) of the device concernedand is used as a guide to the velocity levels that can be ex-pected.

Notes:

• Recommended that this should be less than the actualvalue when converged because this avoids choking duringthe early streamline curvature iterations.

• If simulations from a cold-start (with no restart file) fail toconverge, it may be useful to modify this parameter be-cause it strongly influences the start velocities.

• Not used if the restart initial condition is used.

• If cm_start = 0.0 then 0.25 is used for all calculationsexcept radial turbines where 0.1 is used. The value of 0.25is probably adequate for radial compressors only.

Tolerance level on change in meridional velocity duringstreamline curvature iterations. The value specified is the

tolerance_cm

maximum percentage change in meridional velocity for con-vergence. Iterations stop when all streamlines and all quasi-orthogonals have a lower value than this.

Notes:

• Typical value 0.01 (that is, 0.01%, which is 1 part in10,000).

• If tolerance_cm = 0.0 then 0.01% is used.


Vista TF


• Note that if the meridional velocity is low at a certainpoint in the flow field, it may be necessary to use ahigher value than this.

• Note that the extremely low value of 0.01% does not implythat the solution is as accurate as this, but just providesconfidence that convergence has really been achieved.

Tolerance level on mass flow for internal mass flow iteration.Note that because this controls the convergence of the inner-

toler-ance_mass

most loop, it should be a factor of 2 to 10 lower than thetolerance value for the meridional velocity (above).

Notes:

• Typical value 0.001 (that is 0.001%, which is 1 part in100000).

• If error_max = 0.0 then 0.001% is used.

Factor to reduce the spanwise velocity gradient from the ra-dial equilibrium equation. Normally equal to 1.0 indicating

grad_ree

that the gradient from the radial equilibrium equation is usedwithout change. For calculations with i_ree = 3, ifgrad_ree is set to 0.0, the program takes a meridional ve-locity gradient of 0.0 (that is constant meridional velocityacross the span) and a value between 1.0 and 0.0 reducesthe spanwise gradient of meridional velocity determined bythe radial equilibrium equation by this amount.

Specification of the Geometry Data File (*.geo)

The geometry data file includes sections of text lines that help you to identify the parameters defined here.You should read the section on geometry in Appendix A: A Note on Sign Convention for Angles and Velocit-

ies (p. 127) to become familiar with sign conventions and angle definitions used in this file. An example ofa geometry data file is given in Appendix C: Example of a Geometry Data File (*.geo) for a Radial Impeller (p. 130).

Section 1: Character strings identifying the geometry data (max 72 characters/line)The syntax is:

Character string - title(1)Character string - title(2)Character string - title(3)

Section 2: Number of quasi-orthogonal lines and scale factor (one line)The syntax is:

n_qo scale


n_qo = number of quasi-orthogonal lines from inlet to outletof the domain. From version V1.31 onwards the maximumvalue of this parameter is unlimited.

n_qo

The scaling factor for all geometry data that is input.scale

Notes:





• Usually the geometry data is input in SI units (that is, allvalues are expected in m and not mm) and then this valueis 1.0.

• If the input geometry data comes from a CAD systemthen it may be in mm. In this case, the value of scalemust be 0.001. Similarly the value can be adjusted to allowthe geometry data to be input in other systems of units;for example, inches.

• This scale factor only scales the data in the geometry inputfile and has no effect on other dimensions elsewhere; forexample, it does not scale the reference diameter, whichmust be input with units of metres, in the aerodynamicfile.

• If you specify scale = 0.0, unity is used.

For each quasi-orthogonal, the following data is required to define the flow channel for the meridionalthrough-flow calculation and the meridional spacing of the quasi-orthogonals. Note that some of thisdata is also repeated in the section on the blade geometry. This duplication allows calculations to bemade in a channel that is not the same as the hub and casing line of the actual blade definition (bladecropping).

Section 3: Definition of quasi-orthogonal types and end points (n_qo lines: i = 1 to n_qo)The syntax (of a single line) is:

i r_hub(i) r_shr(i) z_hub(i) z_shr(i) n_blade(i) n_curve(i) i_type(i) i_row(i) i_spool(i)


Number of a particular quasi-orthogonal line.i

Notes:

• The actual value is not used by the program internallybecause it recounts the quasi-orthogonals as they are in-put. The number specified is only used as a guide to thelocation in the input file.

• This allows you to merge two different geometry files of,say, a rotor and stator, to a single stage geometry filewithout the need to renumber the quasi-orthogonals. Inthis case, the same number may appear more than once.In a similar way, a single quasi-orthogonal may be re-moved without the need for renumbering the lines.

Radial coordinate at hub end of quasi-orthogonal [m].r_hub(i)

Radial coordinate at casing end of quasi-orthogonal [m].r_shr(i)

Axial co-ordinate at hub end of quasi-orthogonal [m].z_hub(i)

Axial co-ordinate at casing end of quasi-orthogonal [m].z_shr(i)

Notes on co-ordinates:

• r_hub may not be close to zero; adapt the grid if neces-sary to avoid small values of r_hub .


Vista TF


• The aspect ratio of the quasi-orthogonal lines determinesthe stability of the solver. The lines should not be tooclosely spaced.

• The end coordinates of the leading and trailing edges ofblade rows should be included in the list of coordinates.

• The end coordinates of the leading edge of a splitter vaneshould be included in the list of coordinates.

Number of blades in blade row.n_blade(i)

Notes:

• = 0 in duct regions.

• The number of blades changes at a splitter blade leadingedge in a compressor or at a splitter vane trailing edgein a turbine, and changes again for multiple splitters. Thisis the only information that the program has about thesplitters, so the location of the splitter vane leading ortrailing edge needs to be a quasi-orthogonal line in theinput data.

Number of defining points along the i th quasi-orthogonalline.

n_curve(i)

Notes:

• = 1, a special case for duct stations. This indicates thatthere are 2 defining points (as for n_curve(i) =2) butthat no further information for this calculating station isprovided in section 4 below, because it is already fullydefined by the hub and casing points given in section 3.

• = 2 for a linear calculating plane in which only the endpoints of the quasi-orthogonal are defined. In this case,similar information can be found in section 4.

• > 2 for a non-linear or curved calculating plane.

• The number of defining points can vary from station tostation but n_curve(i) should typically be the samefor all stations because streamline section data is usuallyavailable on a fixed number of spanwise sections.

• Note that the hub and casing geometry information doesnot necessarily have to be the same as that defined insection 4. In this case the data in section 3 will be usedto crop the blade row or to make a section through theblade information in section 4.

Parameter to identify type of calculating station:i_type(i)

1 - for duct region

2 - for non-rotating blade row (stator)

3 - for rotating blade row (rotor)





Notes:

• The program internally identifies which lines are leadingand trailing edges from the changes of type of blade row,and which line is the leading edge of a splitter vane (bythe change in blade number).

• There must be at least two duct calculating stations up-stream of the first blade row, and downstream of the lastblade row.

• A blade row must consist of at least two calculating sta-tions (leading and trailing edge). Typically a radial impellerwill have around 15 calculating stations, because thisgives a 6° turn between each station and improves thecalculation of the curvature terms.

• There must be at least two blade calculating stations up-stream and downstream of a splitter vane leading edge.

• Other types of blade row may be defined at a later stage.

This parameter is used to identify type of blade row and stageof the quasi-orthogonal calculating station. In fact the pro-

i_row(i)

gram can usually identify the type of blade row itself fromthe geometry and the context, so it is not necessary to specifythese values at all and, in the first instance, this parametermay be set to zero. They are included here for special caseswhere the program may have difficulty with the rules thatare coded to identify blade row types.

= n11 - radial compressor inlet guide vane1

= n12 - radial compressor inlet guide vane2

= n13 - radial compressor impeller blade

= n14 - radial compressor diffuser vane

= n15 - radial compressor return channel vane

= n16 - radial compressor axial de-swirl vane

= n21 - axial compressor inlet guide vane1

= n22 - axial compressor inlet guide vane2

= n23 - axial compressor rotor blade

= n24 - axial compressor stator vane

= n25 - axial compressor outlet guide vane

= n31 - radial turbine inlet guide vane1

= n32 - radial turbine inlet guide vane2


Vista TF


= n33 - radial turbine impeller blade

= n34- radial turbine stator vane

= n35- radial turbine outlet guide vane

= n41 - axial turbine inlet guide vane1

= n42 - axial turbine inlet guide vane2

= n43- axial turbine rotor blade

= n44- axial turbine stator vane,

= n45- axial turbine outlet guide vane

Notes:

The value of n determines which stage is being considered,such that a multistage axial compressor with an IGV wouldbegin with values of 121 for the inlet guide vane, continuewith values of 123 for the rotor, and 124 for the downstreamstator, so that the next rotor would be 223, an so on. Adouble row of stators would be denoted as n24 and n25 forthe successive blade rows.

Parameter to identify rotational speed of spool or shaftswhere different blade rows have different speeds.

i_spool

0 single shaft with one speed (ref_n )

1 first shaft with speed (ref_n1 )

2 second spool with second speed (ref_n2 )

3 third spool with third speed (ref_n3 )

Note that counter-rotating blade rows can be dealt with byspecifying negative speeds for the second spool. The programdetermines the number of different spools (n_spool ) fromthe number of different values of i_spool(i) found in thegeometry input file. (The maximum is set to be 3.)

Notes:

• The data is supplied on n_curve lines spaced fairly evenly from hub to casing. For example, ifn_curve = 5, there may be points at 0%, 25%, 50%, 75%, and 100% of span. If n_curve = 2, therewill be just two points, at 0% and 100% span.

• The blade data and quasi-orthogonal data in section 4 may extend outside of the flow channeldefined by the meridional coordinates given in section 3. In a normal calculation, the data overlapspartly with that given in section 3, because the end points of the quasi-orthogonal lines are definedtwice (except for duct calculating stations with n_curve(i) = 1; see above). The flow channeldefined in section 3 is generally congruent with the blade hub and shroud defined in section 4. Theblade, as defined in section 4, may extend outside of the region of the flow channel because this




allows a calculation to be made in a cropped or trimmed flow channel only by changing the datain section 3; section 4 does not need to be changed.

• The end points of the quasi-orthogonal lines, as defined by coordinates r_hub(i) , r_shr(i) ,z_hub(i) , and z_shr(i) , should lie along the quasi-orthogonal lines as defined by r_qo (j,i)and z_qo(j,i) below. In many cases, the end points will be coincident with the blade data, butif this is not the case, it is not acceptable to define end points that do not lie on the blade datapoint.

• All the angles are specified in degrees because this is more convenient in those cases where it maybe necessary to define the geometry by hand, and also allows a simple consistency check, but in-ternally the program converts them into radians. Further description of the angles is provided inAppendix A: A Note on Sign Convention for Angles and Velocities (p. 127).

The sections above define only the hub and casing walls and provide information on the type ofcalculating station. The detailed orientation and position of the curved quasi-orthogonal line andthe details of the blade surface geometry are provided in the next section.

Section 4: Geometry of quasi-orthogonal line and bladeThe syntax (of the single line) is:

i j r-qo(j,i) theta_qo(j,i) z_qo(j,i) thu_qo(j,i) gamma_r_qo(j,i) gamma_z_qo(j,i)


Number of a particular quasi-othorgonal for data input (in-creasing from inlet to outlet). Note that this value is not read

i

in as input data but is simply used as orientation in the datafile when examining the geometry input data.

Number of streamline for data input (increasing from hub toshroud). Note that this value is not read in as input data but

j

is simply used as orientation in the data file when examiningthe geometry input data. Note that for each q-o (i) , thespanwise data is entered (j) before continuing with thenext q-o .

Radial coordinate of point j along q-o (i) [m].r_qo(j,i)

Circumferential coordinate of blade camber line at point(r_qo , z_qo ) [degrees].

theta_qo(j,i)

Note:

• The angular coordinate (theta) is taken as positive in thedirection of rotation and negative in the other direction.

• In a duct region this angle may be zero.

• This angle is not used by the program but helps to visu-alize the blade shape and may be useful for plots of theblade shape.

• In a region where there is a splitter vane this angle is theblade camber angle of the main blade and not of thesplitter.

Axial coordinate of point along quasi-orthogonal [m].z_qo(j,i)

Circumferential thickness of blade at point (r_qo , z_qo ) [m].thu_qo(j,i)


Vista TF


Note:

• In a duct region this thickness should be specified as zero.

• In a region where there is a splitter vane this thickness isthe mean thickness of the main blade and the splitter.

• At leading and trailing edges the value supplied is notused by the program, but the calculating station is takento be at the limit of the chord with zero thickness.

• The thickness is not the thickness normal to the camberline.

Lean angle of the blade with a radial line [degrees] as definedin Appendix A: A Note on Sign Convention for Angles and Velo-

cities (p. 127).

gamma_r_qo(j,i)

Lean angle of the blade with an axial line [degrees] as definedin Appendix A: A Note on Sign Convention for Angles and Velo-

cities (p. 127).

gamma_z_qo(j,i)

Notes:

• This geometry includes the coordinates of the blade camber surface (r-qo(j,i) , theta_qo(j,i) ,z_qo(j,i) ) so that it would theoretically be possible for the program to differentiate this inform-ation to determine the slope angles of the surface (gamma_r_qo(j,i) , gamma_z_qo(j,i) ).This is not done for two reasons. Firstly, experience shows that with the crude grids typically usedfor throughflow calculations, this differentiation would be an unwanted source of error leading topoor estimates of the blade angles, so a system was chosen in which the blade angles are supplied.In fact the value of theta_qo(j,i) is not used by the program and can be specified as zero.Secondly, in many cases the slope angles of a blade row are known (inlet and outlet angles)whereas the circumferential coordinate is unknown.

• This system of geometry with the definition of two angles is designed for radial turbomachineryapplications because it allows the complex shape of three-dimensional blades to be defined by theuse of the two lean angles, gamma_r and gamma_z.

• In conventional axial turbomachinery throughflow programs, it is not usual to define the blade inmuch detail because often simulations are carried out with only inlet and outlet blade angles. Thisis also possible with Vista TF. In a ductflow calculation with only leading and trailing edges, thevalue of gamma_r can be set to 0° . Because the leading and trailing edges are not considered tohave any blade force, this has no effect on the simulation. The value of gamma_z defines the inletand outlet blade angles of sections through the blade at constant radius.

• Vista TF assumes that the geometry is always specified for a clockwise rotation (see Appendix A: A

Note on Sign Convention for Angles and Velocities (p. 127)). If the geometry is correctly specified, anegative rotational speed is used, and Vista TF performs calculations assuming that the shaft is ro-tating in the wrong direction with all the wrong incidences, loading, an so forth. For the case wherethe geometry is specified for counterclockwise rotation, the value of i_flow in the .con file shouldbe specified as a negative number, for example, -1 or -2. This causes the program to internally switchthe angles from positive to negative, and vice-versa, before it proceeds to perform calculations asusual, assuming that the shaft rotates in the clockwise rotation.

• The next sections provide additional blade-row geometry data for use by the correlations in theprogram. Although this data is not always needed, the format of this section includes 8 real para-meters.




Section 5: Additional geometry data (n_curve(i) lines for each blade row)The syntax is:

j throat throat_pos clearance max_thickness te_thickness dummy dummy dummy


Number of a particular streamline for data input (increasingfrom hub to shroud).

j

Throat width of section j [m].throat

Note:

• If the value of zero is input then the program estimatesthe throat width from the blade angles and the bladethickness, taking into account that the throat is close tothe leading edge for compressors and close to the trailingedge for turbines. For radial compressors this estimate isnot particularly accurate and for cases close to choke youshould provide more precise data here.

• For axial compressors it is assumed that the blade has acircular arc camber line and the program includes an es-timate of the throat area based on the geometrical rela-tionships for circular arc blades.

• For other blade types, you should specify the value.

Position of throat on this blade section.throat_pos(i)

Note:

• If the value of zero is input then the program estimatesthe throat position from the blade angles and the bladethickness, taking into account that it is close to the leadingedge for compressors and close to the trailing edge forturbines.

• For radial compressors this estimate is not particularlyaccurate and for cases close to choke you should providemore precise data here.

• For axial compressors it is assumed that the blade has acircular arc camber line and the program includes an es-timate of the throat position based on the geometricalrelationships for circular arc blades.

• For other blade types, you should specify the value.

Tip clearance of hub section [m].tip clearance

Tip clearance of shroud section [m].hub/shroud

Note:

• If the first value is non-zero, this is interpreted as the hubclearance.

• If the last value (n_curve(i) ) is non-zero, this is inter-preted as the casing clearance.


Vista TF


• In a variable stator vane with a hub clearance and aclearance gap for the shaft, it is possible to have non-zerovalues on both the hub and the tip and then both willbe taken into account in the loss correlations.

Maximum normal thickness of blade section [m].max_thickness

Note:

• Although the circumferential thickness of the blade rowis already specified in section 3, the location of the quasi-orthogonal lines may not coincide with the location ofnormal maximum thickness, so this value must be spe-cified separately.

• If the value of zero is specified then the program searchesfor the normal maximum thickness of the blade, as givenin section 3, and uses it.

Trailing edge normal thickness of blade section [m].te_thickness

Note:

• Although the circumferential thickness of the blade rowis already specified in section 3, this value must be spe-cified separately.

• If the value of zero is specified then the program estimatesthe trailing-edge thickness of the blade from the circum-ferential thickness given in section 3, and uses it.

In order to allow for parameters that may be needed byother correlations in the future, the program includes threedummy parameters which should each be set to 0.0.

dummy

Specification of Aerodynamic Data File (*.aer)

The aerodynamic input data file includes lines of text that help you to identify the parameters defined here.Although in some areas this file may appear to be complex, a typical simulation uses only one of the allowedoptions and so, once an input file with the correct format has been established, further use of the file is lesscomplex.

An example of an aerodynamic data file is given in Appendix D: Example of an Aerodynamic Data File

(*.aer) (p. 132).

Section 1: Character strings identifying the aerodynamic data (max 72 characters/line)The syntax is:

Character string – title(1)Character string – title(2)Character string – title(3)

Many options are supplied for specifying the flow data, but typically the options with i_flow = 1(specified mass flow) and i_flow = 5 (specified pressure ratio) are used. Note that i_flow is specifiedin the control file.

Section 2: Reference aerodynamic parameters (depends on value of i_flow in .con file)The syntax is:




ref_mach ref_phi ref_d

if i_flow = 0 and ref_mach < 3, or

ref_u ref_phi ref_d

if i_flow = 0 and ref_u > 3, or

ref_n ref_mass ref_d

if i_flow = 1 and n_spool = 0 or 1, or

ref_n1 ref_n2 ref_mass ref_d

if i_flow = 1 and n_spool = 2, or

ref_n1 ref_n2 ref_n3 ref_mass ref_d

if i_flow = 1 and n_spool = 3, or

ref_n ref_volume ref_d

if i_flow = 2, or

ref_u ref_mass ref_d

if i_flow = 3, or

ref_u ref_volume ref_d

if i_flow = 4, or

ref_n ref_mass ref_d ref_pr

if i_flow = 5, or

ref_n ref_mass ref_d ref_pr n_p_te guess_pr_1 ...

if i_flow = 6, or

ref_n ref_mass ref_d ref_pd

if i_flow = 7, or

ref_n ref_mass ref_d ref_pd n_p_te guess_pd_1 ...

if i_flow = 8, or

ref_n ref_mass ref_d ref_cu

if i_flow = 9.


Vista TF

Note

The very large number of possible ways of specifying the flow and speed appears, at first, tobe slightly overwhelming. Generally i_flow = 1 is used. Note that the reference diameteris given here and not in the geometry file. This is because you may prefer to use the hubdiameter, the tip diameter, the inlet diameter, or the outlet diameter, as a reference valuewithout changing the geometry file.

Note

The geometry definition of Vista TF assumes clockwise rotation. This leads to a certain con-vention for the sign of the blade angles (see Appendix A: A Note on Sign Convention for Angles

and Velocities (p. 127)). In some cases you may have a counterclockwise machine with bladeangles of the opposite sign. To avoid the need to change all the angles specified in the .geofile, an option is provided whereby the value of i_flow is given a negative sign.

A negative value for speed means that the blade is rotating in the counterclockwise direction.


“Iteration to mass flow”i_flow =0

ref_mach = Machine Mach number (based on inlet totalconditions) [-] or reference blade speed [m/sec]. (In this doc-ument, “[-]” means dimensionless.)

Notes:

• If ref_mach < 3 then ref_mach is interpreted asref_mach .

• If ref_mach > 3 then ref_mach is interpreted asref_u .

ref_phi = Inlet flow coefficient (based on total inlet condi-tions) [-]. (In this document, “[-]” means dimensionless.)

ref_d = Reference blade diameter for the definition of flow

coefficient. [m]






ref_n = Machine rotational speed [rpm]

ref_mass = Mass flow [kg/sec]


coefficient. [m]

If the machine has separate spools of different speeds(i_spool(i) > 2) then the speed of each spool can beprovided up to a maximum of three different spools.

ref_n1 = Rotational speed of shaft 1 [rpm]



Counter-rotating blade rows require the second blade rowto be provided with a negative speed.



ref_volume = Volume flow at inlet total conditions [m3/sec]


coefficient. [m]


ref_u = Reference blade speed [m/s]

ref_mass = Mass flow [kg/sec]

ref_d = Reference blade diameter for the definition of theblade speed [m]


ref_u = Reference blade speed [rpm]

ref_volume = Volume flow at inlet total conditions [m3/sec]

ref_d = Reference blade diameter for the definition of theblade speed [m]

“Iteration to pressure ratio”i_flow =5


ref_mass = Mass flow [kg/sec] (estimate of actual massflow but final converged mass flow is determined by thepressure ratio and this only serves as an initial guess)


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coefficient. [m]

ref_pr = Total to static pressure ratio on mean streamline

“Iteration to pressure ratio”i_flow =6


ref_mass = Mass flow [kg/sec] (estimate of actual massflow)


coefficient. [m]

ref_pr = Total to static pressure ratio on mean streamline

n_p_te = Number of trailing edges at which a guessed valueof the pressure ratio is specified

guess_pr_1 = Guessed value of the pressure ratio at thefirst trailing edge

guess_pr_2 = Guessed value of the pressure ratio at thesecond trailing edge

...

guess_pr_n_p_te = This continues up to and includingthe last trailing edge.

Note that if the pressure ratio of the last trailing edge differsto that of ref_pr , than all values at all trailing edges arescaled with the value of ref_pr .

“Iteration to pressure difference”i_flow =7


ref_mass = Mass flow [kg/sec] (estimate of actual massflow but final converged mass flow is determined by thepressure ratio and this only serves as an initial guess)


coefficient. [m]

ref_pd = Total to static pressure difference on meanstreamline

“Iteration to pressure difference”i_flow =8







ref_d = reference blade diameter for the definition of flow

coefficient [m]

ref_pd = Total to static pressure difference on meanstreamline

n_p_te = Number of trailing edges at which a guessed valueof the pressure ratio is specified

guess_pd_1 = Guessed value of the pressure difference atthe first trailing edge

guess_pd _2 = Guessed value of the pressure differenceat the second trailing edge

...

guess_pd_n_p_te = This continues up to and includingthe last trailing edge

“Iteration to outlet swirl”i_flow =9



ref_d = reference blade diameter for the definition of flow

coefficient. [m]

ref_cu = Swirl velocity on mean streamline at rotor outlet


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Note

• The reference blade speed, tip speed Mach number, or Machine rotational speed is alsoneeded for the calculation of a stator blade row. This is because these parameters areused to define various non-dimensional flow and work coefficients and the referenceblade speed is also used to determine the flow velocities for the initial estimate of theflow field (together with parameter cm_start . See section 5 of the .con file specificationgiven in Specification of the Control Data File (*.con) (p. 74)).

• Iteration to a defined pressure ratio makes use of the so-called target pressure ratiomethod of Denton. This requires the program to make a fist guess of the pressure ateach trailing edge of the machine. The algorithm currently incorporated makes a crudeestimate of these, but it has been found that this may not be sufficient to secure conver-gence. For this reason, you can define the first guess of the pressure at each trailing edgeby setting i_flow = 6 (instead of 5).

• A line prepared with data for i_flow = 6 can formally also be used with i_flow = 5or i_flow =1 with no change, so that a calculation can switch from “iteration to pressureratio” to “iteration to mass flow” with no formal change to the aerodynamic input datafile.

Section 3: Reynolds number or viscosityThe syntax is:

ref_re

or

ref_mue


Reynolds number based on ref_u ( ), ref_D ( ),and inlet total conditions [-]. (In this document, “[-]” meansdimensionless.)

ref_re

Dynamic viscosity at the inlet plane and mean inlet totalconditions.

ref_mue

Note

The program identifies which of these parameters has been provided from the absolute valueof the numerical input. If the value is greater than 1.0 [N s m^-2] (or equivalent value in otherunits), it is interpreted as a Reynolds number; if it is less than 1.0 [N s m^-2] but greater than0.0000001 [N s m^-2], it is interpreted as the dynamic viscosity. A value of 0 causes the programto determine the dynamic viscosity from an inbuilt equation for the dynamic viscosity basedon Sutherland’s law and the inlet total temperature.




Section 4: Fluid data (depends on value of i_fluid in .con file)The syntax is:

cp_gas gamma_gas

if i_fluid = 1, which indicates an ideal gas, or

cw_fluid rho_fluid

if i_fluid = 2, which indicates a liquid.


cp_gas = Specific heat at constant pressure [J/kgK]i_fluid = 1

(ideal gas)

gamma_gas = ratio of specific heats [-] (In this document,“[-]” means dimensionless.)

cw_fluid = Specific heat of fluid [J/kgK]i_fluid = 2

(liquid)

rho_fluid = density of liquid [kg/m3]

Section 5: Number of points on the inlet boundary where flow conditions are specifiedThe syntax is:

n_inbc


Number of points at which the inlet flow conditions are spe-cified across the inlet plane.

n_inbc

Note:

• n_inbc < n_sl

• if n_inbc = 1 then only a single value is input and thevalues are constant across the span

Section 6: Fraction of mass flow where inlet conditions are specified (n_inbc values)The syntax is:

f_mass_inbc


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n_inbc values of the fraction of mass along the inletboundary at which inlet boundary conditions are specified.

f_mass_inbc

First value should be 0.0 and last value should be 1.0. Notethat if n_inbc = 1 then this has no function and a dummyvalue can be specified, but this should not be omitted.

Section 7: Pressure on the inlet boundary (n_inbc values which depend on i_inbc in .con file)The syntax is:

pt_inbc

if i_inbc = 0.


Total pressure on the inlet boundary [Pa].pt_inbc

Note that if an incompressible calculation is carried out it isstill necessary to specify the absolute value of the total pres-sure on the inlet boundary.

(i_inbc =0)

Section 8: Temperature on the inlet boundary (n_inbc values, depend on i_inbc in .con file)The syntax is:

tt_inbc

if i_inbc = 0.


Total temperature on the inlet boundary [K].tt_inbc

(i_inbc = 0)

Section 9: Swirl or angle on the inlet boundary (n_inbc values, depend on i_inbc in .con file)The syntax is:

rcu_inbc

if i_inbc = 0, or

alpha_inbc

if i_inbc = 1.


Swirl on the inlet boundary [m2/sec]. Note that this is theproduct of the local radius of the streamline and the local

rcu_inbc

(i_inbc =0) circumferential velocity component and is positive if the swirlis in the forward direction of rotation.





Flow angle on the inlet boundary [°]. Note that this is fromthe axial direction and positive in the direction of rotation.

alpha_inbc

(i_inbc =1) Note also that, if a single value is specified, it is used to calculatethe swirl on the mean streamline of the inlet boundary, and thisswirl is then kept constant across the span. If a constant angleacross the span is required then 2 values need to be specifiedacross the span (n_inbc =2). Experience with radial turbineswith high swirl at the inlet show that the specification of a singlevalue of swirl across the span is more robust than specifying avariation of flow angle across the span.

Section 10 : Aerodynamic model parametersThe syntax is:

eddy f_bl_le f_bl_te


Spanwise mixing parameter (eddy diffusivity).eddy

Notes:

• Typically 0.0001 to 0.001. See Streamline Curvature

Throughflow Theory (p. 118).

• This has no function if i_mix = 0.

• If i_mix = 1 and eddy = 0.0 then a value of eddy =0.0005 will be used.

f_bl_te is the meridional fraction of blade length at theleading edge where the blade is partly transparent to the

f_bl_le

flow (accounts artificially for the increased loading due toincidence). It is recommended that you specify a value of 0.0for both f_bl_te and f_bl_le . If both f_bl_te andf_bl_le are equal to zero then the program estimates thevalues of these from the blade spacing using the equationsgiven in Streamline Curvature Throughflow Theory (p. 118). Ifyou want, you can specify these values. If you specify 0.0 thenthe flow is congruent with the mean blade camber line atthe leading edge. A typically value is roughly equal to theblade spacing.

Fraction of blade length after which the blade is partlytransparent to the flow at the trailing edge (accounts artifi-

f_bl_te

cially for the decreased loading due to deviation as the trail-ing edge is approached). It is recommended that you specifya value of 0.0 for both f_bl_te and f_bl_le . If you specify1.0 then the flow is congruent with the mean blade camberline right up to the trailing edge. If both f_bl_te andf_bl_le are equal to zero then the program estimates thesefrom the blade spacing using the equations given inStreamline Curvature Throughflow Theory (p. 118).


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Specification of Correlations Data File (*.cor)

The input data file includes sections of text lines that help you to identify the parameters defined here; seethe examples in Appendix E: Examples of Correlations Data Files (*.cor) (p. 133). The first part of the file containscontrol parameters that define the layout of the remainder of the input data that is needed. The file is arrangedso that it always has a standard format at the beginning (first 8 lines) but may require different data towardsthe end depending on the type of calculation under consideration (axial compressor, radial turbine, singlestage, multi-stage, an so on). Similar types of simulations always use similar formats for this file, but differenttypes of simulations may require different formats for the latter part of this file.

You specify the empirical data using one of two approaches:

• You specify losses, blockage, and deviation, associated with individual, specifically-defined, quasi-ortho-gonals.

This approach is oriented around the quasi-orthogonals, enabling you to specify different local efficiencyand blockage values for each quasi-orthogonal. Although deviation is only meaningful at the trailingedge, a similar approach is used for deviation to be consistent with losses and blockage.

This approach is recommended for beginners.

• You provide information that enables the program to calculate the needed empirical data for bladerows from built-in correlations.

This approach is oriented around blade rows and requires data to be specified at each blade row trailingedge (or upstream of this – see later).

Note that the correlations used for individual blade rows can be changed from one blade row to another.You can also use the correlations for deviation from one source and the correlations for losses from another.In general, and for simplicity, you should apply the correlations in such a way that all blade rows use thesame correlations and the losses, blockage, and deviation, are also from the same source.

The correlations currently programmed and in preparation can be obtained with the use of the followingparameters for i_loss_type , i_dev_type and i_ewb_type :

i_loss_type / i_dev_type / i_ewb_typeTurbine correla-

tions

1 / 1 / 1Kacker-Okapuu

2 / 2 / 2Dunham-Came

i_loss_type / i_dev_type / i_ewb_typeCompressor cor-

relations

11 / 11 / 11Miller-Wright

12 / 12 / 12Miller-Wright (asmodified by Cal-vert)

If required, you can specify single values of the losses, deviation, and blockage parameters, for the first bladerow or first quasi-orthogonal. These are then used throughout the domain provided that they are not changedagain. In addition, it is possible to apply multiplicative and additive correction factors to the values predictedby the correlations, by the application of “fudge factors” (user-defined corrections). Generally this file doesnot need to be changed once it has been set up, so you might not need to understand all the intricacies of




the many possibilities that it allows, and typically a standard type of correlations file can be establishedwhich can then be used for all subsequent simulations with the same set of correlations.

Examples of some typical correlations data files are given in Appendix E: Examples of Correlations Data Files

(*.cor) (p. 133), showing several specific examples for specific types of calculation.

Section 1: Character strings identifying the correlation data (max 72 characters/line)The syntax is:

Character string – title(1)Character string – title(2)Character string – title(3)

Section 2: Integer control parameters for loss, deviation and blockage models (one line)The syntax is:

i_loss i_dev i_ewb


Determines the loss specification to be used.i_loss

Notes:

• i_loss = 0

No losses are specified and the calculation uses constantentropy. Note, however, that in order to retain similarstructures for the correlations file, the lines described insections 3 and 4 are still needed, but have no effect.

• If i_loss = 1 then a user-defined variation of efficiency,loss coefficient, or dissipation coefficient across the spanis specified at the spanwise positions given in section 4.The number of definition positions across the span andthrough the domain are given in section 3. Different val-ues of the efficiency, loss coefficient, or dissipation coeffi-cient can be specified for different quasi-orthogonal cal-culating stations. A value on the first quasi-orthogonal isalways needed. This value remains constant until changedby the next quasi-orthogonal at which the loss is defined.If only a single value is specified across the span then thisis applied on the mean streamline and each streamlinehas the same entropy rise as on the mean streamline. Ifa calculation with a constant efficiency for all streamlinesis required then the efficiency needs to be specified con-stant on at least two points across the span.

• If i_loss = 2 then built-in loss correlations are used ac-cording to the values given in sections 3 and 4.

Determines the method for calculation of a blade outlet flowangle (deviation or slip).

i_dev

Notes:

• If i_dev = 0 , the flow follows the mean blade camberline given in the .geo file with no deviation. This optionallows a mean S2 though-flow calculation to be carried


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out using the mean stream surface obtained from a seriesof S1 blade-to-blade calculations, provided that these arethen given as the geometry of the camber surface in the.geo file. Note that, in order to retain similar structuresfor the correlations file, the lines described in sections 5and 6 are still needed but have no effect.

• If i_dev = 1 then data is specified in sections 5 and 6 topredict the variation of the flow angle at the blade outletfrom the mean blade camber line across the span. Theinformation can be either in the form of a deviation angle,a specified flow outlet angle, a specified slip factor, or amodification to the cosine rule, according to the type ofblade row.

• If i_dev = 2 then inbuilt correlations are used to determ-ine the flow angle according to the type of blade row asspecified in sections 5 and 6.

Determines the blockage correlation for boundary layers thatis to be used (ewb means “end-wall blockage”)

i_ewb

Notes:

• If i_ewb = 0 then no end-wall blockage is applied. Notethat, in order to retain similar structures for the correla-tions file, the lines described in sections 7 and 8 are stillneeded, but have no effect.

• If i_ewb = 1 then data is specified in sections 7 and 8 topredict the variation of the flow blockage for each quasi-orthogonal and for each streamline. A single value impliesthat a constant blockage value is applied in the wholecalculation domain.

• If i_ewb = 2 then builtin correlations are used to determ-ine the blockage according to the type of blade row asspecified in sections 7 and 8.

Section 3: Loss input data locationsThe syntax is:

n_loss_sl n_loss_qo

or

n_loss_bladerow n_dummy

If i_loss equals 0 or 1 then the losses for each quasi-orthogonal can be specified, and the followingvalues are required:


Number of the spanwise positions for which the loss data issupplied.

n_loss_sl





Number of quasi-orthogonal calculating stations through thedomain on which the loss information is specified.

n_loss_qo

If i_loss equals 2 then the losses for each blade row can be specified, and the following values arerequired:


Number of separate blade rows for which the loss data issupplied.

n_loss_bladerow

A dummy integer value to ensure that line 3 always has twointeger values.

n_dummy

If i_loss equals 0 or 1 then the following version of section 4 is required:

Section 4: User-defined loss data specification (n_loss_qo * n_loss_sl lines)This version of section 4 is applicable when i_loss equals 0 or 1.

The syntax is:

i_qo_loss k_loss f_loss loss


Number of the quasi-orthogonal calculating station on whichthe loss, deviation, and blockage information is specified. The

i_qo_loss

specified values will be applied for all blade rows and calcu-lating stations downstream of this quasi-orthogonal until thevalue is changed by a subsequent section 4 with a new valueof j_qo_loss . The first value of i_qo_loss must be 1.Subsequent lines may change the way in which the lossesare defined.

Parameter to define how the losses are specified. The valueof the polytropic efficiency, the loss coefficient, or the dissip-

k_loss

ation coefficient, determines the entropy increase dependingon the values of k_loss .

Notes:

• If k_loss = 1 then the small-scale static to static poly-tropic efficiency (etapoly ) is specified. This is used insuch a way that the entropy always increases so that, foran accelerating flow with a decrease in static enthalpy, itdefines a turbine efficiency, and for a decelerating flow,it defines a compressor efficiency. This small-scale effi-ciency is applied in blade rows and in ducts.

• If k_loss = 2 then the entropy loss coefficient (xsi ) isspecified. Note that the loss coefficient is the entropy losscoefficient with respect to outlet plane dynamic head foraccelerating blade rows (turbine rotors and stators) andwith respect to the inlet plane dynamic head for deceler-ating blade rows (compressor rotors and stators). An inletguide vane for a compressor is therefore calculated as a


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turbine blade row, and an outlet guide vane for a turbineas a compressor blade row. Like the deviation, this valueis only used at the trailing edge of a blade row.

• If k_loss = 3 then the dissipation loss coefficient (cd )is specified. This is applied in blade rows and in ducts.

• If k_loss = 4 to 9 then various forms of efficiency areused to specify the rotor blade row losses, as follows:

k_loss = 4 total-total polytropic efficiency

k_loss = 5 total-static polytropic efficiency

k_loss = 6 static-static polytropic efficiency

k_loss = 7 total-total isentropic efficiency

k_loss = 8 total-static isentropic efficiency

k_loss = 9 static-static isentropic efficiency

These are applied in blade rows only. The full range is al-lowed, but options 6 and 9 are probably not very relevant.

• If k_loss = 10 then the loss in a stator vane can bespecified as a total pressure loss coefficient.

• If k_loss = 11 then the performance of a stator van canbe specified as a static pressure rise coefficient.

Note

These options have been programmed in such away that different blade rows may have differentvalues of k_loss .

The fraction of the span at which the value of loss applies. Ifonly a single value is given, it is applied at the meanstreamline independent of the value of f_loss .

f_loss

Depending on the value of k_loss , this is interpreted as asmall-scale polytropic efficiency (etapol ), a loss coefficient(xsi ) or a dissipation coefficient (cd ).

loss

If i_loss equals 2 then the following version of section 4 is required:

Section 4: Correlation-based loss data specification (n_loss_bladerow lines)This version of section 4 is applicable when i_loss equals 2.

The syntax (of a single line) is:

i_loss_bladerow i_loss_type factor1 factor2 factor3 factor4 factor5 factor6





Number of the blade row on which the loss information isspecified. The specified values will be applied for all blade

i_loss_bladerow

rows downstream of this blade row until the value is changedby a subsequent section 4 with a new value ofi_loss_bladerow , and then this will again be applieduntil changed. The first value must be 1.

Parameter to define which correlations are used for the bladerow losses. The current loss correlations incorporated intothe method are as follows:

i_loss_type

• i_loss_type = 1

Turbine loss correlations of Kacker and Okapuu

• i_loss_type = 2

Turbine loss correlations of Dunham and Came

• i_loss_type = 11

Compressor loss correlations of Miller and Wright

User-defined multiplication or addition factors to the lossesdetermined by the correlations. This allows the loss correla-

factor1 tofactor6

tions to be modified to improve matching with experimentalor CFD data. These have different functions for the differentcorrelation systems.

factor1 : Multiplication factor on profile losses

factor2 : Multiplication factor on secondary losses

factor3 : Multiplication factor on tip clearance losses

factor4 : Multiplication of penetration of secondary losses

factor5 : Multiplication of penetration of tip clearance losses

factor6 : Not in use

Section 5: Deviation input data locationsThe syntax is:

n_dev_sl n_dev_qo

or

n_dev_bladerow n_dummy

If i_dev equals 0 or 1 then the deviation for each quasi-orthogonal can be specified, and the followingvalues are required:


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Number of spanwise positions for which the flow angle datais supplied.

n_dev_sl

Number of quasi-orthogonal calculating stations on whichthe flow angle information is specified.

n_dev_qo

If i_dev equals 2 then the deviation flow angle data can be specified for each blade row, and the fol-lowing values are required:


Number of separate blade rows for which the flow angle datais supplied.

n_dev_bladerow

A dummy integer value to ensure that section 5 always hastwo integer values.

n_dummy

If i_dev equals 0 or 1 then the following version of section 6 is required:

Section 6: Flow angle data specification (n_dev_qo * n_dev_sl lines)This version of section 6 is applicable when i_dev equals 0 or 1.

The syntax is:

i_qo_dev k_dev f_dev dev


Number of the quasi-orthogonal calculating station on whichthe deviation information is specified. The specified values

i_qo_dev

will be applied for all blade row trailing edges downstreamof this quasi-orthogonal until the value is changed by a sub-sequent section 6 with a new value of i_qo_dev . The firstvalue must be 1.

Determines the type of outlet flow angle calculation, as fol-lows:

k_dev

• If k_dev = 1 then the deviation angle is specified (in de-grees).

• If k_dev = 2 then the relative outlet flow angle is spe-cified (in degrees).

• If k_dev = 3 then a slip factor is specified and appliedon the mean line (dimensionless). Note that if no valueis specified then the Wiesner slip factor is used. Only re-commended for radial impellers and not for mixed flowstages, which should use deviation.

• If k_dev = 4 then a slip factor is applied at each radiusof the trailing edge (dimensionless). Note that if no valueis specified then the Wiesner slip factor is used. Only re-commended for radial impellers and not for mixed flowstages, which should use deviation.

• If k_dev = 5 then a correction to the flow angle calcu-lated by the cosine rule is specified. If zero is specified for





this correction, then the cosine rule is used to calculatethe relative flow angle at the outlet for all radii. If a non-zero value is specified then this modifies the flow angleby this constant amount (in degrees). A positive valueincreases the deviation.

The fraction of the span of at which the value of the deviation(and similar things) applies. If only a single value is given, itis applied at the mean streamline independent of its value.

f_dev

Depending on the value of k_dev , this is interpreted as adeviation angle, flow angle, slip factor, or correction to thecosine rule.

dev

If i_dev equals 2 then the deviation for each blade row must be specified using the following versionof section 6:

Section 6: Flow angle data specification (n_dev_bladerow lines)This version of section 6 is applicable when i_dev equals 2.

The syntax is:

i_bladerow_dev i_dev_type factor1 factor2 factor3 factor4 factor5 factor6


Number of the blade row on which the deviation informationis specified. The specified values will be applied for all blade

i_bladerow_dev

row trailing edges downstream of this quasi-orthogonal untilthe value is changed by a subsequent section 6 with a newvalue of i_bladerow_dev . The first value must be 1.

Parameter to define which correlations are used for the bladerow deviations. The current deviation correlations incorpor-ated into the method are as follows:

i_dev_type

• i_dev_type = 1 (Kacker Okapuu)

Turbine deviation using the cosine rule.

• i_dev_type = 2 (Dunham and Came)

Turbine deviation using the cosine rule.

• i_dev_type = 11 (Miller Wright)

Compressor deviation correlations of Miller and Wright.

User-defined multiplication or addition factors to the devi-ations determined by the correlations. This allows the devi-

factor1 tofactor6

ation correlations to be modified to improve matching withexperimental or CFD data. These have different functions forthe different correlation systems.

factor1 : Additive factor in degrees (°) on hub deviation

factor2 : Additive factor in degrees (°) on mean deviation


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factor3 : Additive factor in degrees (°) on tip deviation




Section 7: Blockage input data locationsThe syntax is:

n_ewb_sl n_ewb_qo

or

n_ewb_bladerow n_dummy

If i_ewb equals 0 or 1 then the blockage for each quasi-orthogonal can be specified, and the followingvalues are required:


Number of spanwise positions for which the blockage datais supplied.

n_ewb_sl

Number of quasi-orthogonal calculating stations on whichthe blockage information is specified.

n_ewb_qo

If i_ewb equals 2 then the blockage correlation can be specified for each blade row, and the followingvalues are required:


Number of separate blade rows for which the blockage issupplied.

n_ewb_bladerow

A dummy integer value to ensure that section 7 always hastwo integer values.

n_dummy

If i_ewb equals 0 or 1 then the blockage for each quasi-orthogonal must be specified using the followingversion of section 8:

Section 8: End wall blockage data specification (n_dev_qo * n_dev_sl lines)This version of section 8 is applicable when i_ewb equals 0 or 1.

The syntax is:

i_qo_ewb k_ewb f_ewb ewb


Number of the quasi-orthogonal calculating station on whichthe blockage information is specified. The specified values

i_qo_ewb

will be applied for all blade rows and calculating stationsdownstream of this quasi-orthogonal until the value is





changed by a subsequent section 4 with a new value ofj_qo_ewb . The first value must be 1.

Determines the type of blockage calculation. Has no effectbecause the blockage is input in only one form as below.

k_ewb

The spanwise location of the value of the blockage. If only asingle value is given, it is applied at all streamlines.

f_ewb

End-wall boundary layer blockage is specified. A value of 0.05represents 5% blockage of the flow channel by the end-wall

ewb

boundary layers. If zero is specified then there is no end-wallboundary layer blockage. Typically a constant value is spe-cified across the whole span, but this parameter can be variedacross the span to allow for the higher blockage in the end-walls related to blade ends with tip clearance.

If i_ewb equals 2 then the following version of section 8 is required:

Section 8: End wall blockage data specification (n_dev_qo * n_dev_sl lines)This version of section 8 is applicable when i_ewb equals 2.

The syntax is:

i_bladerow_ewb i_ewb_type factor1 factor2 factor3 factor4 factor5 factor6


Number of the blade row on which the blockage informationis specified. The specified values will be applied for all blade

i_bladerow_ewb

row trailing edges downstream of this quasi-orthogonal untilthe value is changed by a subsequent section 6 with a newvalue of i_bladerow_ewb . The first value must be 1.

Parameter to define which correlations are used for the blade-row blockage. The current blockage correlations incorporatedinto the method are as follows:

i_ewb_type

• i_ewb_type = 1

No blockage consistent with Kacker Okapuu.

• i_ewb_type = 2

No blockage consistent with Dunham and Came.

• i_ewb_type = 11

Compressor blockage correlations of Miller and Wright.

User-defined multiplication or addition factors to the blockagedetermined by the correlations. This allows the end-wall

factor1 tofactor6

blockage correlations to be modified to improve matchingwith experimental or CFD data. These have different functionsfor the different correlation systems.




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Specification of the Output Data File (*.out)

The output data file includes lines of text in ASCII format that show the results of the simulation. The fileconsists of several sections:

Section 1: Input dataAt the start of this file, a list of the input data files that were used is recorded in this file so that a recordof the file names is available.

INPUT DATA FILES: Control data file: agard.con Geometric data file: agard.geo Aerodynamic data file: agard.aer Correlation data file: agard.cor Restart data file: agard.rstOUTPUT DATA FILES: Results file: agard.out Tecplot data file: impeller.txt CFD-POST data file: agard.csv Convergence history file: agard.hst Interface output file: agard.int

Section 2: Reference dataThe program uses the input data to set up the values of various other parameters; for example, wherethe reference mass flow is specified, the reference volume flow is calculated. The values of all otherparameters not included in the input specification are given in this section. In addition, the internalcalculation of the damping factors is provided. Other data listed here relates to the program's own es-timates of the throat area and the throat position. An example is given below.

Example radial compressor calculation:

Reference flow parameters-------------------------

Mass flow distribution across streamlines: 0.000 0.062 0.125 0.188 0.250 0.312 0.375 0.438 0.500 0.562 0.625 0.688 0.750 0.812 0.875 0.938 1.000

Inlet distribution across streamlines: Fraction of flow: 0.00 Total pressure: 100000.00 Total temperature: 293.00 Inlet swirl: 0.00

Ideal gas calculation

gamma_gas gas_m r_gas cp_gas 1.400 3.500 287.200 1005.200

ref_pt(bar) ref_tt ref_rhot ref_soundt 1.0000 293.00 1.1884 343.23

Reference rotational direction: clockwise

ref_d ref_u ref_omega ref_n0.2700 398.10 2948.91 28160.0




ref_mach ref_phi ref_mass ref_volume1.1599 0.0667 2.3000 1.94

ref_re ref_mue 6963614.0 0.00001834

ref_n1 ref_n2 ref_n3 28160.0 0.0 0.0

Simulation with no spanwise mixing

Iterate to mass flow, ref_mass = 2.30000

First approximation of streamline positionstaken from an earlier calculation

Estimated max. thicknesses for blade row 1span 0.00000 0.17343 0.34429 0.51305 0.67879 0.84126 0.97669 1.00000thickne 0.00351 0.00319 0.00291 0.00266 0.00241 0.00215 0.00195 0.00191

User-input throat widths for blade row 1span 0.00000 0.17343 0.34429 0.51305 0.67879 0.84126 0.97669 1.00000throat 0.01760 0.02137 0.02460 0.02732 0.02959 0.03141 0.03257 0.03276

Estimated throat positions for blade row 1span 0.00000 0.17343 0.34429 0.51305 0.67879 0.84126 0.97669 1.00000throat_pos 0.00969 0.02084 0.03424 0.04835 0.06224 0.07573 0.08688 0.08882

Empirical correlation data

User specified losses User specified deviation No blockage specified

Relaxation factor calculation of Wilkinson------------------------------------------

Maximum aspect ratio: 6.0667at calculating station: 5damp_sc (user input): 0.2500damp_sc (Wilkinson): 0.0577

Warning: damp_sc reduced by the code to the value suggested by Wilkinson

Section 3: Short history of the convergenceThe .out file contains a statement about convergence of the results. A converged calculation includesa header such as the following:

************************************************ Vista TF converged -it_main: 6 ** ** cm_error(%) p_error(%) mass_error(%) ** 0.042 0.000 0.000 ************************************************* Global performance ** ** mass (kg/s): 0.093200 ** est. choke: 0.107995 ** t-t t-s s-s ** eta_p: 0.8453 0.7415 ** eta_s: 0.8553 0.7583 ** pr: 0.5800 0.5374 0.6100 ** er (1/pr): 1.7243 1.8609 1.6392 ** power (kW): -5.4316 ************************************************

A more detailed convergence history is output to the history file, which is described inSpecification of

Convergence History Data File (*.hst) (p. 117).


Vista TF

Section 4 : Simulation results on quasi-orthogonal planes and streamlinesResults are provided at every quasi-orthogonal requested (see control file parameter i_print_plane )in the level of detail requested (parameter i_print_level ). The data is provided across the span foreach streamline. If the number of streamlines is greater than 9 then data for every second streamline isgiven. The structure of this data and the information provided varies depending on the type of calculationstation. The example below is for a radial impeller leading edge:

Quasi-orthogonal - i = 3 n_blade n_curve i_type i_row i_spool 13 6 3 0 0Rotor blade - leading edgeAt throat (or just upstream of throat)CompressorRadial impellerThroat area = 0.00274713Annulus choke parameters: dm_dcm = 0.79601 Mach_eff = 0.45166choke mass at this q_o = 7.72100choke_mass of machine = 7.72100choke_mass of this blade row = 7.72100current_mass at this q_o = 6.70000inlet mass flow = 6.70000Factor on slope of ree: grad_re = 1.00000 cm_guess_save = 152.57564Flow parameters - print_level=1streamline 1 3 5 7 9 11 13 15 17r [m] 0.07612 0.08753 0.09759 0.10647 0.11445 0.12176 0.12855 0.13493 0.14100z [m] -0.13500-0.13500-0.13500-0.13500-0.13500-0.13500-0.13500-0.13500-0.135001/rc[1/m] -5.996 1.353 2.758 2.818 2.475 1.984 1.438 0.864 0.244throat mm 23.00 24.41 25.66 26.77 27.40 27.84 28.17 28.30 29.00f_sl [-] 0.17503 0.17777 0.18110 0.18431 0.18734 0.19021 0.19295 0.19556 0.19806f_qo [-] 0.00000 0.17593 0.33098 0.46775 0.59076 0.70340 0.80807 0.90652 1.00000f_bl [-] 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000f_thr [-] 0.02584 0.03400 0.04157 0.04823 0.05408 0.05923 0.06379 0.06785 0.07150gamma_in 1.00000 1.00000 1.00000 1.00000 1.00000 1.00000 1.00000 1.00000 1.00000gamma_out 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000cm [m/s] 146.87 142.25 145.30 149.18 152.57 155.22 157.11 158.32 158.87- error % 0.0001 -0.0002 0.0001 0.0001 0.0001 0.0001 0.0000 -0.0002 -0.0001- max 169.57 166.48 168.30 172.19 174.87 177.33 179.61 180.96 186.11cu [m/s] 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00M_cm [-] 0.437 0.423 0.432 0.444 0.455 0.463 0.469 0.472 0.474M_crit[-] 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000 1.000M_rel [-] 0.765 0.837 0.914 0.985 1.050 1.109 1.163 1.213 1.260beta_fl° -55.19 -59.65 -61.79 -63.21 -64.34 -65.33 -66.23 -67.08 -67.90beta_bl° -43.03 -46.77 -50.17 -52.99 -55.37 -57.46 -59.30 -60.92 -62.35incidence 12.16 12.88 11.62 10.22 8.98 7.86 6.93 6.16 5.55p [bar] 0.8706 0.8778 0.8730 0.8669 0.8614 0.8571 0.8540 0.8519 0.8510t [K] 282.38 283.04 282.60 282.04 281.54 281.14 280.84 280.66 280.57rho[kg/m3] 1.0742 1.0806 1.0764 1.0710 1.0661 1.0623 1.0595 1.0577 1.0569A*/A 0.9485 0.9758 0.9935 0.9998 0.9980 0.9907 0.9799 0.9666 0.9517m/m_max 0.8661 0.8545 0.8633 0.8664 0.8725 0.8753 0.8747 0.8749 0.8536m_prime 75.46 84.55 95.91 106.88 116.97 126.15 134.46 141.98 148.76m_pr_max 87.12 98.94 111.09 123.37 134.07 144.11 153.70 162.27 174.26ch_ratio 0.8662 0.8545 0.8634 0.8664 0.8725 0.8753 0.8748 0.8749 0.8537Flow parameters - print_level=2eps [°] 12.82 14.30 12.54 10.34 8.13 6.01 4.00 2.08 0.23psi [°] 77.18 75.70 77.46 79.66 81.87 83.99 86.00 87.92 89.77c [m/s] 146.87 142.25 145.30 149.18 152.57 155.22 157.11 158.32 158.87w [m/s] 257.28 281.50 307.34 330.98 352.35 371.83 389.80 406.55 422.31u [m/s] 211.24 242.91 270.83 295.46 317.60 337.88 356.73 374.45 391.29wu [m/s] -211.24 -242.91 -270.83 -295.46 -317.60 -337.88 -356.73 -374.45 -391.29M_abs [-] 0.437 0.423 0.432 0.444 0.455 0.463 0.469 0.472 0.474alpha_fl° 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00pt [bar] 0.9921 0.9921 0.9921 0.9921 0.9921 0.9921 0.9921 0.9921 0.9921tt [K] 293.00 293.00 293.00 293.00 293.00 293.00 293.00 293.00 293.00s [J/kgK] 2.29 2.29 2.29 2.29 2.29 2.29 2.29 2.29 2.29ds[J/kgK] 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00ewb [-] 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500 0.0500Loading parameters - print_level=3w_s [m/s] 287.34 314.82 342.24 366.60 388.17 407.50 425.12 441.51 456.87w_p [m/s] 227.21 248.18 272.45 295.36 316.53 336.16 354.47 371.59 387.74M_ws [-] 0.855 0.936 1.018 1.091 1.157 1.215 1.268 1.318 1.364




M_wp [-] 0.676 0.738 0.810 0.879 0.943 1.002 1.058 1.109 1.157C_btob [-] 0.234 0.237 0.227 0.215 0.203 0.192 0.181 0.172 0.164

Specification of the Text Data Files (*.txt)

The text data files include lines of text in ASCII format which are intended as input for various softwarepackages for producing plots of the converged results. The text files can be used as input data for Tecplot.Standard layout (.lay ) files for Tecplot have been prepared which allow typical diagrams to be producedon the basis of this data. The information is structured in such a way that it can just as easily be used byExcel or some other similar program with an appropriate interface.

In fact, after running the program, several standard .txt files for Tecplot are produced: one covering thewhole flow field and one for each blade row. The flow field data is written in the file prefix.txt , and theblade-row data in the files row_01_prefix.txt , row_02_prefix.txt , and so on, whereby the numberof the files refers to the blade rows numbered from the start of the computational domain. You only needto provide the name of one of these files in the vista_tf.fil file, because the others are automaticallygenerated and numbered by the program.

Some standard Tecplot layout files have been prepared that operate on the .txt files to produce typicalplots that are needed during the design of a component. For example, the files used for radial compressorimpellers are called: flowfield_2d_v_2_0.lay and rc_impeller_row1.lay . The first of theseprepares a plot showing the 2D meridional channel with contours of constant parameters (such as meridi-onal velocity, swirl velocity, static temperature, Mach number, cm_error and so on) and the second preparesblade loading plots for a typical blade row. The layout file (.lay ) determines the format of the plot andthe ASCII .txt file contains the data to be plotted. The format and the scales can also be changed on-linewithin Tecplot by clicking on the screen. Other Layout files for other cases (ac = axial compressor, hp = hy-draulic pump, ht= hydraulic turbine, rt = radial turbine, at= axial turbine) are also available and these canbe easily customized (scales, parameters and so on).

The standard Tecplot layout files (.lay ) have all been written to work on the data in text files named im-peller.txt and row_01_impeller.txt , and so on. The first dataset, impeller.txt , contains in-formation for the contour plots showing the meridional velocity and other parameters projected on themeridional plane and the second, row_01_impeller.txt , contains the various blade loading parametersfor an individual blade row. If the case concerned has several blade rows then there is also a file calledrow_02_impeller.txt , row_03_impeller.txt , and so on; there is one file for each blade row. Anew layout file is needed for each blade row. The letters “impeller” in this name rely on the fact that theprefix for the .txt file has this name in the vista_tf.fil file.

Other prefixes will produce .txt files containing the prefix as specified in the vista_tf.fil file. In thiscase, the layout files need to be modified; the layout files can be opened in a text editor; the name of the.txt file is on the second line. This name can then be changed to match the name given as a prefix in thevista_tf.fil file. Alternatively, the same layout files can be used for several cases if all data that needsto be plotted always retains the prefix name impeller ; the text output file from vista_tf always hasthe name impeller.txt in the vista_tf.fil file.

Generally, a good strategy is to set up the .aero , .cor , .con , and .txt files with a certain prefix in thevista_tf file and to let these keep the same names for all runs on a particular case because they normallydo not change as the design progresses. It then remains necessary to switch the .geo files around to lookat different impellers, or else the prefix for the .geo file can be retained and the cases can be distinguishedby simply putting them into different directories to distinguish the different cases.

The data in the prefix.txt file is in approximately the following format:

TITLEFlow field data for whole flow field from hub to shroud for all q-os


Vista TF

Variables = '"r" "z" "cm" "cu" "cr" "cz" "p" "t" "pt" "tt" "s" "h" "q_o" "error" "choke_ratio""M_rel" "M_abs" "alpha_flow" "beta_flow" "1/rc" "beta"'

"r" Radius coordinate"z" Axial coordinate"cm" Meridional velocity"cu" Swirl velocity"cr" Radial velocity"cz" Axial velocity"p" Static pressure"t" Static temperature"pt" Total pressure"tt" Total temperature"s" Entropy"h" Static enthalpy“q_o” an integer identifying the particular type of q-o“error” Meridional velocity error in %"choke_ratio" choke ratio (ratio of local mass flow to choke flow at this location)"M_rel" Relative Mach number"M_abs" Absolute Mach number"alpha_flow" Absolute flow angle [°]"beta_flow" Relative flow angle [°]"1/rc" Curvature ( inverse of the radium of curvature)"beta” Blade angle [°]

The data in the row_01_prefix.txt file is approximately in the following format:

TITLEData on hub, mean and tip streamlines for all blade rows from LE to TEand data along leading edge and trailing edge of all blade rows

VARIABLES =VARIABLES = "i_type", "f_bl", "M", "M_s", "M_p", "w", "w_s", "w_p",..."p", "p_s", "p_p", "c_btob", "c_htos", "beta_bl", "beta_fl", "dep_angle", "gamma_in", ...gamma_out", "f_qo", "de_haller", "cp_ideal", "incidence", "deviation", "lambda", ..."df_lieblein", "zweifel" "c_lift", "c_zw""f_bl" Fraction of meridional distance along the blade"M" Mean mid-passage Mach number (relative to blade)"M_s" Suction side Mach number"M_p" Pressure side Mach number"w" Mean mid-passage velocity (relative to blade)"w_s" Suction surface velocity"w_p" Pressure surface velocity"p" Static pressure in mid-channel between two blades"p_s" Suction surface static pressure"p_p" Pressure surface static pressure"c_btob" Blade to blade loading parameter (c_btob = (w_s-w_p)/w, that is the difference between suction surface and pressure surface velocities divided by the mid-channel velocity"c_htos" Hub to shroud loading parameter (c_htos = (cm_shroud – cm_hub)/ cm_mean, that is the difference between the meridional velocity on the casing and the hub divided by the mean velocity."beta_bl" Blade angle in degrees [°]"beta_fl" Flow angle in degrees [°]"dep_angle" Departure angle in degrees [°]"gamma_in" Blending functon at blade inlet"gamma_out" Blending function at blade outlet"f_qo" fractional distance along q-o"de_haller" De Haller number (de_haller = w2/w1, that is outlet/ inlet relative velocity"cp_ideal" Ideal static pressure recovery coefficient ( Cpideal = 1 – (de_haller)**2 )"incidence" Incidence at the leading edge [°]"deviation" Deviation at the trailing edge[°]"lambda" Work coefficient ( lambda = (h2-h1)/u**2, that is Deltah / u squared)"df_lieblein" Lieblein Diffusion Factor (see below)"zweifel" Zweifel loading parameter (see below)"c_lift" Lift coefficient (see below)"c_zw" Lift coefficient times solidity (see below)




Note that the values of the last four parameters have been included mainly for axial blade rows. Each ofthem includes the blade solidity (ratio of chord to spacing) in its definition. In radial machines, the spacingand solidity change with radius along the streamline. There is no generally agreed method to calculate theseparameters for radial machines, so the mean value of the spacing has been selected in the following definitionsused in Vista TF. In any case, caution is suggested in the use of these parameters for radial machine bladerows because the experimental basis for limit values has generally been derived from axial machines.

Lieblein diffusion factor (df_lieblein)

Zweifel coefficient (zw)

Lift coefficient (CL)

where

Zwiefel number (c_zw)

Specification of the CFD-Post Output Files (*.csv)

The text data files *prefix.csv include lines of text in ASCII Comma Separated Variable format files (.csv )which are intended as input for CFD-Post for plotting purposes, using the user surface data format. For detailsof this format, see the documentation provided with CFD-Post.

In the current .csv files, the following data is available for each grid node:

[Name]Vista-TF[Data]X [m], Y [m], Z [m], Cm [m/s], Cu [m/s], Cr [m/s], Cz [m/s], p [bar], t [K], s [J kg^-1 K^-1],h [J/kg], q_o [], error [], M_rel[], M_abs[], rc [m^-1]

The file global_prefix.csv contains a list of parameters, whereby these are specified as:

Name 1 = value1 [units]Name 2 = value2 [units]

Separated by comment lines which begin with “#”.

In addition, there are four additional files produced for each blade row from 1 to n:

row_0n_hub_prefix.csvrow_0n_mean_prefix.csvrow_0n_tip_prefix.csvrow_0n_loading_prefix.csv


Vista TF

These contain essentially similar information to the row_0n_prefix.txt files described above, but thisis split into four separate files: one for the hub, one for the mean span, one for the tip, and one for theloading parameters.

Specification of Convergence History Data File (*.hst)

The convergence history data file includes lines of text in ASCII format that show the convergence of thesimulation. This contains details of the convergence of the main iterative procedures, and extensive detailsof the terms in the radial equilibrium equation for each stream tube and calculating plane. It is rare for thisto be examined in any depth, but this can be useful to identify problems if the solution fails to converge.

Section1: Input DataAt the start of the .hst file, the input data is recorded. This is essentially in the same format as the inputfiles. At the start of this file, there is a list of the names of the input data files that were used. This inform-ation can be useful if an error occurs in the input data because the .hst file records only the data thathas been successfully read into the program.

Section 2: Convergence DataAt every iteration, a summary of the iteration progress is provided. It looks like this:

History of the main iteration loop---------------------------------- it_main: 1 error_cm(%): 100.000 at i_qo: 0 j_sl: 0 it_mass: 11 at i_qo: 1 it_main: 2 error_cm(%): 38.940 at i_qo:10 j_sl:17 it_mass: 11 at i_qo: 1 it_main: 3 error_cm(%): 30.036 at i_qo:10 j_sl:17 it_mass: 11 at i_qo: 3 it_main: 4 error_cm(%): 24.600 at i_qo:10 j_sl:17 it_mass: 11 at i_qo: 4 it_main: 5 error_cm(%): 20.939 at i_qo:10 j_sl:17 it_mass: 11 at i_qo: 5 it_main: 6 error_cm(%): 18.306 at i_qo:10 j_sl:17 it_mass: 11 at i_qo: 6 it_main: 7 error_cm(%): 16.403 at i_qo:10 j_sl:17 it_mass: 11 at i_qo: 6

.....

it_main: 284 error_cm(%): 0.013 at i_qo: 7 j_sl:17 it_mass: 1 at i_qo: 1 it_main: 285 error_cm(%): 0.012 at i_qo: 7 j_sl:17 it_mass: 1 at i_qo: 1 it_main: 286 error_cm(%): 0.011 at i_qo: 7 j_sl:17 it_mass: 1 at i_qo: 1 it_main: 287 error_cm(%): 0.010 at i_qo: 7 j_sl:17 it_mass: 1 at i_qo: 1 it_main: 288 error_cm(%): 0.009 at i_qo: 7 j_sl:17 it_mass: 1 at i_qo: 1

Section 3: Streamline Curvature Solution DataAt every quasi-orthogonal, details of the terms in the radial equilibrium equation for each stream tubeare provided. This can be useful in identifying errors and also helpful to determine the magnitude ofthe terms in the equations. “rhs” is the value of the right hand side of the radial equilibrium equation,giving the square of the gradient of the meridional velocity.

The streamline curvature solution data looks like this:

Quasi-othogonal - i = 5 n_blade n_curve i_type i_row i_spool 9 8 3 0 0Radial equilibrium parameters -print_level = 4rhs 1049.90 1059.86 871.10 684.48 510.68 349.39 199.63 55.28ret 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00ret_dh 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00ret_tds 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00ret_drcu 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00sct 1049.90 1059.86 871.10 684.48 510.68 349.39 199.63 55.28sct_rc 641.48 681.97 558.43 431.70 315.91 211.42 118.25 34.87sct_dcm 408.43 377.89 312.67 252.78 194.78 137.97 81.38 20.40bft 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00dft 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00cm_error% -0.0010 0.0002 -0.0003 -0.0007 -0.0007 -0.0003 0.0003 0.0010f_mixing 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.00001/rc 2.853 4.466 4.153 3.505 2.773 2.016 1.261 0.517 -0.209cm 137.936 145.590 152.396 157.708 161.716 164.594 166.473 167.450 167.568rcu 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000 0.000




drcu/dm 47.323 53.336 48.562 35.419 15.376 -11.226 -43.868 -81.313-123.649s 1.885 1.885 1.885 1.885 1.885 1.885 1.885 1.885 1.885bl_block 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000 0.0000

Software Limitations

There are several potential sources of errors and uncertainties in all CFD simulations, all of which are extremelyrelevant in turbomachinery applications using a throughflow program, such as Vista TF. The standard cat-egorization of such errors is into the following groups:

• Numerical errors

• Model errors

• Application uncertainties

• User errors

• Software errors

and these are briefly described next.

Numerical errors decrease the quality of simulations and can be reduced but not eliminated. The control ofnumerical error is largely a matter of adequate grid design, appropriate numerical discretization, and adequatelevel of convergence. An example in Vista TF is the approximation of the streamlines by a piecewise parabolathrough 3 points. In a throughflow calculation the so-called model errors probably outweigh all other sourcesof error. These are related to the fact that the equations that are solved do not really describe the real flowparticularly adequately (in this case the solution is for inviscid, circumferentially-averaged mean values onwidely spaced grid lines). Application uncertainties may be only partly in your control and are related to thedetail with which aspects of the geometry are accurately known or specified. Typical examples would be alack of knowledge about the fillet radii in the geometry for a blade row calculation, or not having correctinformation about the inlet boundary conditions for a specific calculation. User errors relate to incorrect useof the program, such as making use of incorrect control parameters to control the calculation. With regardto software errors, every reasonable precaution to ensure the accuracy and reliability of the Vista TF programhas been taken. However, when using the program, especially for a critical design, you should first completean appropriate validation and calibration process. A good turbomachinery analysis procedure dictates thatany program, including Vista TF, must be thoroughly tested with non-critical data before there is any relianceon it.

Streamline Curvature Throughflow Theory

Vista TF is a general purpose streamline curvature throughflow program for the analysis of all types of tur-bomachinery, but with special emphasis on single stage centrifugal machines, such as radial pumps, turbines,and compressors, which can usually not be calculated by other throughflow programs.

The program has the ability to compute radial blade rows in both compressors and turbines, and the swirlingflows in the radial channels of such machines. This is possible because the blade and channel geometry isdefined in a very general way independent of the meridional streamline direction.

This section of the documentation is intended for readers who are not familiar with throughflow methods;it provides a general introduction to the streamline curvature axisymmetric meridional throughflow calculationmethod. Some details are given in Casey and Robinson (2008) [5] (p. 125). This section includes a list oftechnical papers on the subject.

The following topics are discussed:The EquationsThe Mean Stream Surface


Vista TF

The GridDuctflow and ThroughflowIterative Solution ProcedureInitial EstimateRadial Equilibrium EquationCombination of Velocity Gradient and Continuity EquationsRelaxation FactorsStreamline curvatureEquations for Enthalpy and Angular MomentumBoundary ConditionsEmpirical DataBlade-to-blade SolutionSpanwise MixingStreamline Curvature Throughflow Theory: Bibliography

The Equations

The equations that are solved are:

• The continuity equation

• The energy equation (Euler equation of turbomachinery)

• A suitable equation of state

• The inviscid momentum equation for the flow on the mean axisymmetric stream surface

Although these equations are inviscid and do not include frictional forces, the effect of the losses are includedby empirical changes to the entropy in the equation of state, such that the final solution has a density andpressure field consistent with the presence of losses in the flow.

The Mean Stream Surface

This blade-like surface may be regarded as being obtained by averaging all flow properties in the circumfer-ential direction, or as being the flow on a mean stream surface between the blade rows, whose orientationis roughly determined by the blade camber surface. The flow blockage caused by the blades is roughly fixedby the circumferential blade thickness of the blades. It is often known as the S2 meridional stream surface,in contrast to the S1 blade-to-blade surface, and in fact corresponds to the so-called S2m surface in thetheory of Wu (1952) [22] (p. 126). See Figure : S1 and S2 Stream Surfaces in the Theory of Wu (1952) (p. 120).Note that it has an arbitrary orientation in the circumferential direction and that the flow in the mean streamsurface is determined by the slope angles of the surface to the axial and the radial directions, both of whichneed to be specified in the geometrical input data.




Figure: S1 and S2 Stream Surfaces in the Theory of Wu (1952)

The Grid

The grid for the calculation is based on the streamlines of the mean circumferentially averaged flow in themeridional direction, and fixed calculating stations which are roughly normal to the streamlines. The meridi-onal streamline grid is not fixed, apart from the hub and shroud streamlines on the annulus walls, butchanges continually during the iterations so that location of the final streamlines is a result of the solutionThe fixed calculating stations are orientated with the blade row leading and trailing edges and are oftenknown as quasi-orthogonals because they are normally nearly orthogonal to the streamlines. The quasi-or-thogonals can be in duct regions, that is in the blade-free space upstream and downstream of blade rows,at the leading and trailing edges of the blade rows (which actually are also generally considered to be inthe duct region) and internally within the blade rows. See Figure : Quasi-orthogonal Calculating Stations in

an Axial Compressor Stage Calculation (p. 121). The computational results are available only at the pointswhere the streamlines cross the quasi-orthogonals. In comparison with modern CFD methods, a very crudegrid is used with typically 9 to 17 streamlines and 3 to 15 quasi-orthogonals per blade row, giving 50 to 300nodes per blade row in comparison to 100 000 to 500 000 in modern CFD simulations.


Vista TF

Figure: Quasi-orthogonal Calculating Stations in an Axial Compressor Stage Calculation

In many early streamline curvature programs, the quasi-orthogonals were generally straight radial lines fromhub to casing placed roughly at the location of the leading and trailing edges, but given the more extensiveuse of lean and sweep in modern designs, and the natural leading edge and trailing edge curvature arisingfrom the variable stagger across the span in most rotors, curved quasi-orthogonals of arbitrary orientationare more appropriate. The use of a grid involving meridional streamlines, all of which proceed smoothlyfrom the inlet plane to the outlet plane of the calculation domain, assumes that there is no reverse flow,and thus operation points with reverse flow in the mean meridional flow (even at the design point) cannotbe calculated by this method.

Ductflow and Throughflow

Earlier methods, which did not include blade internal calculating planes, are often known as duct flow

methods because only planes in the duct regions between the blades, and at the leading and trailing edges,are used. Throughflow refers to methods in which internal planes within each blade row are included asshown in Figure : Quasi-orthogonal Calculating Stations in an Axial Compressor Stage Calculation (p. 121). Inthroughflow methods, the component of the blade force acting along the direction of the quasi-orthogonalcan be included in the meridional throughflow equations, so that some global aspects of the effect of theblade lean on the meridional flow can be included. This is not possible in duct flow methods without someempirical adjustment of the pressure gradients.

Iterative Solution Procedure

The solution method is iterative in terms of several variables (primarily the meridional velocity, but also thedensity, streamline location, and other variables), all of which progressively converge to a final convergedsolution within a fairly complex structure of three nested iterations. In this convergence procedure, manyvariables lag behind the main iteration for changes in the meridional velocity, so that during one iterationleading to an update of the meridional velocity, many parameters are treated as constant and are then up-dated based on the new estimate of the meridional velocity prior to the next iteration. It is assumed thatthis has no effect on the solution provided that a converged solution for all variables is reached.




Initial Estimate

The initial solution generally comprises a first guess of streamline positions (typically by dividing the flowpath into equal areas at each quasi-orthogonal) and flow variables at all the grid points (that is, the junctionpoints between the variable streamlines and the fixed quasi-orthogonals). This is then successively refinedas a result of each iteration. Once a first estimate of the streamline positions is in place then various termsin the radial equilibrium equation, such as the curvature of the streamlines or the rate of change of meridi-onal velocity along the streamlines, can be determined.

Radial Equilibrium Equation

The momentum equation on the mean stream surface is a form of the radial equilibrium equation, givinga velocity gradient equation for the gradient of the meridional velocity along a calculating station, or quasi-orthogonal:

This equation is given in many text books (see Cumpsty (1989) [6] (p. 125)) and is not repeated here. It relatesthe velocity gradient to the shape and the current positions of the streamlines, to the orientation of themean stream surface, and to the flow parameters and their gradients from the previous iteration. In itssimplest form, this equation is the well-known simple radial equilibrium equation of turbomachinery flows,which gives the relationship between the radial gradient of the axial velocity and the gradient of the swirlin the radial direction, as follows:

In its general form the radial equilibrium equation takes into account flow gradients, streamline curvature,and radial flows, and allows a general arbitrary orientation of the quasi-orthogonal lines. The key differencebetween the simple radial equilibrium equation and the more general equation is the inclusion of thestreamline curvature terms, and it is these terms that give their name to the method. There are several formsof this velocity gradient equation, but the one used here follows the method of Denton (1978) [7] (p. 125),but takes into account the blade force terms as described in chapter 3.4 of the book by Cumpsty (1989)[6] (p. 125).

Combination of Velocity Gradient and Continuity Equations

The velocity gradient equation is solved in combination with a method for finding the correct velocity levelon the mean streamline that ensures that the velocity along the quasi-orthogonal satisfies the continuityequation giving the correct mass flow across the quasi-orthogonal. See Figure : Continuity and the Velocity

Gradient Used in Determining the Meridional Velocity Level (p. 123). The meridional velocity on the meanstreamline is specified in the innermost iteration, integrated across the flow channel with the help of themeridional velocity gradient, and then continually updated until the mass flow is correct. This requires somecare to ensure that the method converges for all mass flows up to the choking mass flow. In this iteration,the density is also needed in the continuity equation. In fact there are two values of the density that canbe used, corresponding to supersonic or subsonic flow. In this method, no attempt is made to distinguishthese during the innermost iteration; the density is simply taken as constant at the value from the previousiteration, and automatically takes on the supersonic or subsonic value as the iteration converges.


Vista TF

Figure: Continuity and the Velocity Gradient Used in Determining the Meridional Velocity

Level

Relaxation Factors

The meridional velocity distribution along the quasi-orthogonal determines the spacing of the streamlinesof the meridional flow, and hence the meridional streamline positions. These positions are continually updatedas the program converges. Generally, it is not acceptable to use the newly calculated positions of thestreamlines directly from one iteration to the next, but a damping factor (often much less than unity) is re-quired to factor the streamline shifts to obtain convergence. A big weakness of streamline curvature methodsis that the required damping factor becomes very small when the quasi-orthogonal lines are closely spaced,and so improved accuracy through more calculating planes causes a large increase in calculating time. Forthis reason, a relatively coarse grid (compared to CFD computations) is used, leading to calculations thattake just a few seconds on a modern PC. The problem with closely spaced quasi-orthogonals is related tothe large errors in the estimated streamline curvature when a small error in the streamline position is present.It is for this reason that many methods do not include blade internal calculation stations because theseautomatically decrease the spacing between adjacent quasi-orthogonals.

Streamline curvature

The streamline positions can be used to interpolate new blade element data appropriate to their currentlocation and to find the slopes, curvatures, and derivatives of the flow parameters along the streamlines.This data is needed in the radial equilibrium equation (velocity gradient equation; see Radial Equilibrium

Equation (p. 122)). The accuracy and stability of streamline curvature methods is related to the prediction ofthe curvatures of the streamlines. Several different numerical methods for this have been examined. In thecurrent method, the curvatures are calculated with a parabolic approximation through three adjacent pointsalong the streamline.

Equations for Enthalpy and Angular Momentum

In the region between blade rows, the total enthalpy and angular momentum may be considered to beconvected along the meridional streamlines from the previous station. The entropy is also convected butrises due to the additional losses between the calculating stations. In a blade row, the changes in momentumand enthalpy are calculated from the Euler equation on the assumption that the flow follows the meanstream surface. The mean blade stream surface is roughly orientated in alignment with the camber surfaceof the blade, but methods are needed for finding the true fluid flow direction taking into account the incidenceand deviation of the flow from the mean blade surface. This is generally dealt with using empirical correlationsfor outlet angle, deviation, or slip factor.

Boundary Conditions

At the inlet plane (first quasi-orthogonal) you are generally required to specify the variation of total pressure,total temperature, and angular momentum or flow angle, together with the gas data and information on




the mass flow at the outlet plane. For calculations with choked flows, it is not possible to calculate with themass flow, making it necessary to calculate with specified outlet static pressure, such that the mass flow isa result of the simulation.

Empirical Data

Additional empirical methods are used to provide data for the loss production, for the boundary layerblockage, and for the deviation of the flow direction from the mean blade camber surface, so that the effectof viscosity can be taken into account. In fact Denton (1978) [7] (p. 125) argues that “in many applications,throughflow calculations are little more than vehicles for inclusion of empiricism in the form of loss, deviationand blockage correlations, and their accuracy is determined by the accuracy of the correlations rather thanthe numerics”. The three main effects of the empirical data are:

• In the equation of state, a change in the entropy leads to a pressure loss for a given value of the totalenthalpy.

• In the continuity equation, the blockage due to the boundary layer displacement effect leads to ahigher value of the meridional velocity.

• In the momentum equation, the deviation of the flow from the blade direction leads to a change in thecalculated swirl velocity.

Thus, although the basic inviscid equation of motion used by the method is inherently incapable of predictingentropy rises through the machine, some effects of losses can be included. There are numerous possiblecombinations of data for the empirical information, based on various definitions of loss coefficients, dissipationcoefficients, efficiencies, and so on, and this leads to the largest source of confusion in the data preparationfor throughflow programs, and a large and complex array of branching “IF” statements within a typicalthroughflow program to deal with the alternatives. In making this program, a single form of loss definitionhas been included based on the entropy rise.

Blade-to-blade Solution

The mean stream surface provides the flow field in the meridional plane through the turbomachine. Generallythe engineer also needs information on the blade surface velocity and Mach number distributions, so themeridional solution needs to be combined with a blade-to-blade method to find blade surface velocities.This may be either a simple approximation or a more accurate solution of the blade-to-blade flow equations.The more accurate methods enable the exact location of the mean stream surface of the flow to be determinedat different blade-to-blade planes, so this can also lead to a further iteration in which the mean stream surfaceis no longer considered as fixed. Such iterative solutions are often known as S1/S2 solutions (the S1 surfacebeing the blade-to-blade surface and the S2 surface being the meridional surface. See Figure : S1 and S2

Stream Surfaces in the Theory of Wu (1952) (p. 120)). This technique has generally been replaced these daysby fully 3D CFD solutions with mixing planes, but is still of historical interest. The simpler methods generallyuse a linear approximation for the velocity variation from suction surface to pressure surface. These can beexpected to produce sensible results only when a sufficient number of internal blade row calculating stationsare included in the grid, probably 5 as the minimum.

Spanwise Mixing

A major shortcoming of the basic streamline curvature method is the neglect of the spanwise transport ofangular momentum, energy, and losses in the direction normal to the streamlines. By definition, athroughflow program is based on the assumption that the flow remains in concentric streamtubes as itpasses through the turbomachine, and no mass transfer occurs across the meridional streamlines which arethe streamtube boundaries. In a duct region of a throughflow calculation, enthalpy, angular momentum(swirl), and entropy are taken to be conserved along the meridional streamlines. In reality, there are several


Vista TF

mechanisms that lead to an apparent spanwise transport of fluid relative to flow on the mean streamlines,as follows:

• Non-axisymmetric blade-to-blade stream surfaces as a result of streamwise vorticity being shed by theblades (stream-surface twist)

• Secondary flows in the end-wall boundary layers and in the blade boundary layers

• Wake momentum transport downstream of blade rows

• Tip clearance flows with tip clearance vortices

• Turbulent diffusion

As a result of not modeling these effects, throughflow programs in which realistic loss levels are specifiedfor the end-wall regions often predict unrealistic profiles of the loss distribution after several stages becausethere is no mechanism for the high losses generated near the end walls to be mixed out. The simplest ap-proach to deal with this problem is to specify unrealistic loss distributions across the span that avoid highlevels in the end walls. In fact, in preliminary design calculations, this is often adequate. A useful approxim-ation is to specify a mean-line value of loss coefficient or efficiency and to assume that the entropy generatedby the losses is the same on each stream-tube. This approximates a complete mixing of the entropy distri-bution across the span.

Several more sophisticated methods to include more detailed physics of these mixing processes have beenattempted so that realistic loss distributions can be specified. The common approach is to model the spanwisemixing as turbulent diffusion, even though some of the effects are due to deterministic flow features. Evenwith throughflow programs in which spanwise mixing is incorporated, it is still generally not possible tofully incorporate the very high loss levels close to the end walls. Vista TF includes these effects as turbulentdiffusion across the streamlines.

Streamline Curvature Throughflow Theory: Bibliography

[1] G. G. Adkins and L. H. Smith. “Spanwise mixing in axial flow turbomachines”. Trans ASME Journal of Engin-

eering for Power , Vol. 104. pg. 97-110. 1982.

[2] P. M. Came. “Streamline curvature throughflow analysis”. Proc. First European Turbomachinery Conference,

VDI Berichte 1185. pg. 291. 1995.

[3] M. V. Casey and O. Hugentobler. “The prediction of the performance of an axial compressor stage with

variable stagger stator vanes”. VDI Berichte Nr. 706. pg. 213-227. 1988.

[4] M. V. Casey and P. Roth. “A streamline curvature throughflow method for radial turbocompressors”. I. Mech.

E. Conference C57/84. 1984.

[5] M. V. Casey and C. J. Robinson. “A new streamline curvature throughflow code for radial turbomachinery”.ASME TURBOEXPO 2008, ASME GT2008-50187. Berlin. 2008.

[6] N. A. Cumpsty. Compressor aerodynamics. Longman Scientific. New York. 1989.

[7] J. D. Denton. “Throughflow calculations for axial flow turbines”. Trans ASME, Journal of Engineering for Power,

Vol 100. 1978.

[8] J. D. Denton and C. Hirsch. “Throughflow calculations in axial tubomachines”. AGARD Advisory Report No.

175 AGARD-AR-175. 1981.




[9] S. J. Gallimore. “Spanwise mixing in multistage axial flow compressors: part II throughflow calculations including

mixing”. Trans. ASME, Journal of turbomachinery, Vol. 108. pg. 10-16. 1986.

[10] I. K. Jennions and P. Stow. “The quasi-three-dimensional turbomachinery blade design system, Part I:

Throughflow analysis, Part II: Computerized system”. Transactions of the ASME, Journal of Engineering

for Gas Turbines and Power Vol. 107. pg. 308-16. 1985.

[11] I. K. Jennions and P. Stow. “The importance of circumferential non-uniformities in a passage averaged quasi-

three-dimensional turbomachinery design system”. Transactions of the ASME, Journal of Engineering for

Gas Turbines and Power Vol. 108. pg. 240-5. 1986.

[12] K. I. Lewis. “Spanwise transport in axial-flow turbines: Part 2 - Throughflow calculations including spanwise

mixing”. Trans. ASME, Journal of turbomachinery, Vol. 116. pg. 187-193. 1984.

[13] B. Liu, S. Chen, and H. F. Martin. “A primary variable throughflow code and its application to last stage reverse

flow in LP steam turbine”. Paper: IJPGC2000-15010, Proc. Int. Joint Power Generation Conference, July23-26. Miami Beach, Florida. 2000.

[14] H. Marsh. “A digital computer program for the through-flow fluid mechanics in an arbitrary turbomachine

using a matrix method”. Aeronautical Research Council R and M 3509. 1968.

[15] C. Hirsch and J. D. Denton. “Throughflow calculations in axial turbomachines”. AGARD Advisory report No.

175, AGARD-AR-175. 1981.

[16] K. I. Lewis. “Spanwise transport in axial flow turbines: part 2 - throughflow calculations including spanwise

transport”. Trans. of ASME, Journal of Turbomachinery, Vol. 116. pg. 187-193. 1994.

[17] R. A. Novak. “Streamline curvature computing procedures for fluid flow problems”. Trans. of ASME, Journal

of Engineering for power, Vol 89. pg. 478-490. 1967.

[18] M. Schobeiri. Turbomachinery Flow Physics and Dynamic Performance. Springer. Berlin. 2005.

[19] L. H. Smith. “The radial equilibrium equation of turbomachinery”. Trans. ASME Journal of Engineering forPower, Vol 88. pg. 1-12. 1966.

[20] D. H. Wilkinson. “Streamline curvature methods for calculating the flow in turbomachines”. Report No

W/M(3F). English Electric. Whetstone, England. pg. 1591. 1969.

[21] D. H. Wilkinson. “Stability, convergence, and accuracy of two-dimensional streamline curvature methods

using quasi-orthogonals”. paper 35, I.Mech.E. Convention. Glasgow. 1970.

[22] C. H. Wu. “A general theory of three-dimensional flow in subsonic, and supersonic turbomachines of axial,

radial and mixed-flow types”. Trans. ASME, Nov. 1952. pg. 1363-1380. 1952.

[23] C. C. Yeoh and J. B. Young. “Non-equilibrium throughflow analyses of low-pressure, wet steam turbines”.ASME J. Eng. for Gas Turbines & Power, Vol 106. pg. 716-724. 1984.

Appendices

The following appendix topics are available:Appendix A: A Note on Sign Convention for Angles and VelocitiesAppendix B: Example of a Control Data File (*.con)Appendix C: Example of a Geometry Data File (*.geo) for a Radial Impeller


Vista TF

Appendix D: Example of an Aerodynamic Data File (*.aer)Appendix E: Examples of Correlations Data Files (*.cor)Appendix F:TroubleshootingAppendix G:The RTZTtoGEO Program

Appendix A: A Note on Sign Convention for Angles and Velocities

When looking along the axis of the machine in the direction of flow we have a cylindrical coordinate system(r, theta, z) (or (r, θ , z)) . The angular coordinate (theta) is taken as positive in the clockwise direction andnegative in the anti-clockwise direction. The normal case considered by Vista TF is clockwise rotation whenlooking along the axis in the direction of the flow so that the angular coordinate increases in the rotationaldirection. See Figure : Coordinate System used by Vista TF (p. 127) below.

Figure: Coordinate System used by Vista TF

The sign convention for velocity values is that an axial velocity component in the positive axial direction ispositive, a radial component in the positive radial direction is positive, and a circumferential component inthe positive angular direction (direction of rotation) is positive.

Blade lean angles are then defined from the axial and radial directions in a similar way using the rotationaldirection as a basis. As you move along an axial rotor blade in the axial direction of a clockwise rotatingmachine then the blade angle theta steadily decreases as the blade is sloped backwards against the rota-tional direction (radial impeller outlet angles are generally also backswept). In a stator vane the angular co-ordinate increases as you step along the blade in the meridional direction. The rate of change of the angularcoordinate with the meridional direction then defines the sign of the blade angle, and this applies for theblade angles, flow angles and also applies to the blade lean angles. See below.

For example, in an axial compressor rotor where the blades lean back from the direction of rotation, thetabecomes more negative as you move along the blade from the leading edge (LE) to the trailing edge (TE).In a compressor stator, theta becomes more positive as you move along the blade. This rule works for axial,radial, and mixed flow compressors, provided the meridional direction is used as a basis. In a turbine stator



Appendices

theta also increases positively from LE to TE and, in a turbine rotor, theta decreases from LE to TE. There aresome exceptions to this rule, related to high camber at leading edges to adapt the flow to the incomingflow direction.

Note

Vista TF uses the rules outlined above to identify the type of machine from the geometrical dataof the blade angles in the geometry input file, so you do not have to specify this.

Definition of Blade Lean Angles

Consider a point q on a radial impeller blade camber surface, as shown in Figure : Definition of Angles (p. 128).

We can define the blade lean angles, and as the angle made by the blade fibers with a radial lineand the angle made with an axial line, as follows:

Figure: Definition of Angles

Notes on :

• This is the blade lean to the radial direction.

• This angle is zero for a blade comprising purely radial blade elements, so is generally close to zero foraxial blade rotor rows (which tend to have no lean) and centrifugal impeller leading edges or radialturbine trailing edges.

• It is non-zero for blades with lean. If, when moving along the blade in the radial direction, the lean isagainst the direction of rotation then it is negative and lean in the direction of rotation is positive.


Vista TF

• A radial compressor impeller with a purely radial blade at impeller outlet (no backsweep) would have

=0° and corresponds to the back-sweep angle in a typical back-swept radial impeller. For an

impeller with 30° of back-sweep, would be negative (-30°) at the trailing edge. Note that, in somesign conventions, the back-sweep angle would be given a positive value, but in Vista TF, it is negative.

• In a the diffuser of a radial pump or compressor stage, this angle corresponds to the diffuser bladeangle and would be typically between 60° and 70° at the leading edge, and would decrease throughthe blade row.

Notes on :

• This is the blade angle measured from the axial direction in the direction of rotation.

• In an axial blade element (or close to the leading edge of a typical radial impeller or the trailing edgeof a radial turbine impeller), this is the blade camber angle. At the inlet to an axial blade row, this isthe blade inlet angle; at the outlet, it is the blade outlet angle.

• In a typical rotor blade, it is negative and, in a typical stator, it is positive. Note that the common excep-tions would be turbine rotors with a low degree of reaction and compressor rotor roots with very highturning.

• In a compressor where the flow is turned by the blade rows towards the axial direction, the absolutevalues decrease from the leading edge to the trailing edge whereas in a turbine where more swirl isadded to the flow, the absolute values increase from the leading edge to the trailing edge.

• For a blade with purely axial blade elements (as in a typical 2D diffuser and at a radial impeller outletwith no rake angle), this angle is zero.

Definition of Meridional Streamline Inclination Angle or Pitch Angle

The angle is the inclination of a meridional streamline to the axial direction:

which on the hub and casing walls becomes the meridional slope angle of the walls.

Definition of Blade Angle

Internally the program uses the angles and to calculate , which is the effective blade angle measured

from the meridional direction. is defined as:

Notes on :

• The wrap angle is taken as positive in the direction of rotation. This is consistent with the flow angledefinition used by the program.



Appendices

• This angle is zero for a blade in which the wrap angle does not change in the meridional direction, such

as an axial strut in an axial channel or a radial strut in a radial channel, where .

• If the wrap angle increases in the meridional direction then the blade angle is positive. If the wrap angledecreases in the meridional direction then the blade angle is negative.

• Note that the actual value of the blade angle as seen by the flow is dependent on the lean angle ofthe meridional streamline, and is not an absolute fixed value for a certain blade. Thus a change in themeridional direction of the flow at an impeller outlet with lean changes the value of the blade angle.

Appendix B: Example of a Control Data File (*.con)

The following is a described example of a control data file:

Three lines to identify the run (maximum 72 characters per line):

PCA stageControl parameters for typical radial impeller5 May 2008

Two lines for the integer control parameters:

n_sl max_it_main max_it_mass9 500 10

Two lines for integer control parameters for output data and the use of the restart file:

i_print_plane i_print_level i_print_units i_display i_restart i_interface 4 5 0 0 0 0

Two lines for integer control parameters for various models and reference parameters:

i_expert i_flow i_fluid i_inbc i_mass i_mix i_ree 0 1 0 0 0 0 0

Two lines for convergence and damping factors:

damp_sc damp_vl cm_start tolerance_cm tolerance_mass grad_ree 0.25 0.25 0.2 0.01 0.005 1.00

Appendix C: Example of a Geometry Data File (*.geo) for a Radial Impeller

The following is a described example of a geometry data file:

Three lines to identify the run:

PCA Stage from .rtzt fileThickness converted to tangential thickness10 blades and 1 splitter

Two lines for the number of quasi-orthogonal lines:

n_qo scale23 1.00000

A section that defines the quasi-orthogonal type and end points:

i r_hub r_shr z_hub z_shr n_blade n_curve i_type i_row i_spool1 0.00069 0.05594 -0.04959 -0.04959 0 1 1 0 02 0.00224 0.05215 -0.03682 -0.03757 0 1 1 0 03 0.00702 0.04941 -0.02481 -0.02527 0 1 1 0 04 0.01189 0.04776 -0.01284 -0.01277 0 1 1 0 05 0.01357 0.04720 -0.00004 -0.00018 10 5 3 0 0


Vista TF

6 0.01447 0.04728 0.00570 0.00371 10 5 3 0 07 0.01609 0.04758 0.01128 0.00759 10 5 3 0 08 0.01832 0.04809 0.01664 0.01145 10 5 3 0 09 0.02108 0.04884 0.02175 0.01526 20 5 3 0 010 0.02463 0.04993 0.02700 0.01930 20 5 3 0 011 0.02867 0.05132 0.03188 0.02325 20 5 3 0 012 0.03314 0.05305 0.03637 0.02706 20 5 3 0 013 0.03799 0.05513 0.04045 0.03068 20 5 3 0 014 0.04318 0.05759 0.04408 0.03407 20 5 3 0 015 0.04866 0.06040 0.04726 0.03717 20 5 3 0 016 0.05440 0.06358 0.04995 0.03988 20 5 3 0 017 0.06035 0.06709 0.05214 0.04216 20 5 3 0 018 0.06646 0.07087 0.05379 0.04393 20 5 3 0 019 0.07271 0.07488 0.05485 0.04514 20 5 3 0 020 0.07902 0.07901 0.05538 0.04575 20 5 3 0 021 0.08033 0.08032 0.05544 0.04585 0 1 1 0 022 0.08164 0.08164 0.05548 0.04592 0 1 1 0 023 0.08295 0.08295 0.05550 0.04597 0 1 1 0 0

A section that defines the quasi-orthogonals and the blade geometry:

i j r_qo theta_qo z_qo thu_qo gamma_r_qo gamma_z_qo5 1 0.01357 0.32039 -0.00004 0.00255 -0.18038 -23.156545 2 0.02198 0.26684 -0.00008 0.00244 -0.36249 -32.520255 3 0.03038 0.21411 -0.00015 0.00251 -0.34266 -41.271895 4 0.03879 0.26814 -0.00016 0.00243 -0.00979 -49.732305 5 0.04720 0.29630 -0.00018 0.00234 -0.18913 -57.432246 1 0.01447 -9.69106 0.00570 0.00269 1.88713 -23.089476 2 0.02267 -8.14852 0.00518 0.00256 0.41685 -31.316986 3 0.03087 -7.40827 0.00464 0.00243 -0.99339 -39.399576 4 0.03908 -6.96808 0.00417 0.00230 -2.04619 -47.449926 5 0.04728 -6.75726 0.00371 0.00218 -3.95792 -54.902817 1 0.01609 -18.29413 0.01128 0.00262 3.70754 -22.858217 2 0.02396 -15.68568 0.01033 0.00248 1.15036 -30.472417 3 0.03183 -14.35239 0.00936 0.00234 -1.75718 -37.836967 4 0.03970 -13.58089 0.00846 0.00220 -3.70752 -45.357647 5 0.04758 -13.16589 0.00759 0.00206 -6.69381 -52.398178 1 0.01832 -25.28463 0.01664 0.00254 4.70103 -22.816468 2 0.02576 -22.28703 0.01531 0.00241 1.41759 -29.881468 3 0.03320 -20.61659 0.01398 0.00227 -2.35690 -36.526128 4 0.04065 -19.60303 0.01270 0.00212 -5.03581 -43.434548 5 0.04809 -18.99898 0.01145 0.00196 -8.73336 -50.000399 1 0.02108 -30.92988 0.02175 0.00248 4.74907 -23.146109 2 0.02802 -28.02047 0.02011 0.00234 1.11611 -29.563309 3 0.03496 -26.23881 0.01846 0.00220 -2.97754 -35.524979 4 0.04190 -25.07781 0.01685 0.00204 -6.21556 -41.740889 5 0.04884 -24.32487 0.01526 0.00188 -10.40615 -47.7916010 1 0.02463 -36.00322 0.02700 0.00242 3.85677 -23.9725410 2 0.03096 -33.42982 0.02507 0.00228 0.15779 -29.5665810 3 0.03728 -31.67995 0.02313 0.00213 -3.84908 -34.8360010 4 0.04361 -30.43321 0.02121 0.00197 -7.49971 -40.2443210 5 0.04993 -29.55790 0.01930 0.00182 -12.07824 -45.6758611 1 0.02867 -40.35207 0.03188 0.00236 2.23718 -25.2645011 2 0.03435 -38.17139 0.02974 0.00222 -1.42539 -29.8948111 3 0.04001 -36.55263 0.02757 0.00207 -5.15749 -34.4920411 4 0.04567 -35.29039 0.02542 0.00192 -8.89269 -39.1210211 5 0.05132 -34.35094 0.02325 0.00177 -13.85353 -43.8584112 1 0.03314 -44.26280 0.03637 0.00232 0.10221 -26.9747412 2 0.03816 -42.42247 0.03407 0.00217 -3.48507 -30.5620812 3 0.04314 -40.96080 0.03175 0.00203 -6.83731 -34.5293212 4 0.04811 -39.72235 0.02942 0.00188 -10.45941 -38.4080012 5 0.05305 -38.76700 0.02706 0.00173 -15.90754 -42.2855813 1 0.03799 -47.91006 0.04045 0.00228 -2.40966 -29.0783213 2 0.04233 -46.32055 0.03805 0.00214 -5.94640 -31.5610413 3 0.04663 -45.00031 0.03562 0.00200 -8.93117 -34.8894713 4 0.05090 -43.80060 0.03317 0.00185 -12.32638 -38.0738013 5 0.05513 -42.85755 0.03068 0.00171 -18.25871 -40.8899714 1 0.04318 -51.39712 0.04408 0.00226 -5.26535 -31.5263414 2 0.04685 -49.96856 0.04163 0.00212 -8.83099 -32.8249614 3 0.05047 -48.75090 0.03914 0.00198 -11.46588 -35.5458514 4 0.05405 -47.58476 0.03663 0.00184 -14.51275 -38.1537414 5 0.05759 -46.66554 0.03407 0.00170 -20.92644 -39.61549



Appendices

15 1 0.04866 -54.78108 0.04726 0.00224 -8.53323 -34.2014915 2 0.05168 -53.43857 0.04478 0.00211 -12.12520 -34.3099915 3 0.05464 -52.27642 0.04227 0.00197 -14.44340 -36.4535115 4 0.05755 -51.13094 0.03975 0.00184 -17.13253 -38.5572715 5 0.06040 -50.22395 0.03717 0.00170 -23.67359 -38.4039716 1 0.05440 -58.09399 0.04995 0.00224 -12.36035 -36.9130616 2 0.05678 -56.77929 0.04747 0.00211 -15.80725 -36.0202016 3 0.05910 -55.62589 0.04497 0.00198 -17.90732 -37.5502516 4 0.06137 -54.47843 0.04245 0.00185 -20.39385 -39.1142516 5 0.06358 -53.55910 0.03988 0.00172 -26.48486 -37.3714817 1 0.06035 -61.35160 0.05214 0.00227 -16.87176 -39.3144017 2 0.06211 -60.02598 0.04967 0.00214 -19.92706 -37.8809917 3 0.06382 -58.83913 0.04719 0.00201 -21.91242 -38.6909817 4 0.06548 -57.66538 0.04469 0.00188 -24.33144 -39.5717717 5 0.06709 -56.69062 0.04216 0.00175 -29.09953 -36.7604718 1 0.06646 -64.56377 0.05379 0.00231 -22.10267 -40.9656618 2 0.06763 -63.20368 0.05134 0.00220 -24.62539 -39.6160118 3 0.06875 -61.94636 0.04888 0.00207 -26.48127 -39.6530418 4 0.06983 -60.72039 0.04641 0.00195 -28.81198 -39.7095018 5 0.07087 -59.63480 0.04393 0.00181 -31.57298 -37.0659219 1 0.07271 -67.72621 0.05485 0.00241 -27.77629 -41.3437419 2 0.07330 -66.32376 0.05243 0.00231 -29.91973 -40.6214119 3 0.07384 -64.96857 0.05000 0.00218 -31.51785 -40.0610619 4 0.07437 -63.66663 0.04757 0.00202 -33.54181 -39.5478319 5 0.07488 -62.40934 0.04514 0.00194 -34.26011 -38.7280020 1 0.07902 -70.87669 0.05538 0.00263 -32.69635 -39.9227920 2 0.07904 -69.41995 0.05297 0.00260 -34.43144 -39.8309720 3 0.07902 -67.94505 0.05056 0.00239 -36.32393 -39.9147020 4 0.07901 -66.52396 0.04815 0.00205 -37.25527 -39.7831820 5 0.07901 -65.01019 0.04575 0.00216 -37.35707 -41.84796

A section for additional geometry data:

j throat throat_pos clearance max_thick te_thick dummy1 dummy2 dummy31 0.00000 0.00000 0.00000 0.00000 0.00000 0.00 0.00 0.002 0.00000 0.00000 0.00000 0.00000 0.00000 0.00 0.00 0.003 0.00000 0.00000 0.00000 0.00000 0.00000 0.00 0.00 0.004 0.00000 0.00000 0.00000 0.00000 0.00000 0.00 0.00 0.005 0.00000 0.00000 0.00000 0.00000 0.00000 0.00 0.00 0.00

Appendix D: Example of an Aerodynamic Data File (*.aer)

The following is a described example of an aerodynamic data file:

Three lines to identify the aerodynamic data:

Radial stage at design flowideal gas5 May 2008

Two lines for the reference aerodynamic parameters, which depend on the value of i_flow in the .confile. Assuming i_flow = 1:

ref_n ref_mass ref_d60000.0 1.00 0.15804

Two lines for the Reynolds number:

Re_ref0.0

Two lines for the fluid data, which depends on the value of i_fluid in the .con file. Assuming i_fluid= 1 (for ideal gas):

cp_gas gamma_gas1005.2 1.40

Two lines for the number of points on the inlet boundary where flow conditions are specified:


Vista TF

n_inbc1

Lines for the fraction of the inlet boundary where flow conditions are specified (n_inbc values):

f_inbc0.0

Lines for the pressure on the inlet boundary (n_inbc values, which depend on i_bc in the .con file). As-suming i_bc = 0:

pt_inbc98000.0

Lines for the temperature on the inlet boundary (n_inbc values, which depend on i_bc in the .con file).Assuming i_bc = 0:

tt_inbc293.0

Lines for swirl on the inlet boundary (n_inbc values, which depend on i_bc in the .con file). Assumingi_bc = 0:

rcu_inbc0.00

Two lines for the mixing model and blade transparency model parameters:

eddy f_bl_le f_bl_te0.0001 0.0 0.0

Appendix E: Examples of Correlations Data Files (*.cor)

EXAMPLE 1

The following example of a correlations data file is for a radial compressor. For most radial compressor orpump impeller calculations, the only parameter that changes is the small-scale polytropic efficiency. Notethat a single value of the empirical information for flow outlet angle is specified (k_dev = 3 implies the useof a slip factor, and because k_dev is specified as 0.0 the program calculates the slip factor from the Wiesnercorrelation).


Typical correlations file for radial compressorsmall-scale efficiency, slip factor of 0.0 (so Wiesner) and no blockage5 May 2008

Two lines for integer data:

i_loss i_dev i_ewb1 1 0

Two lines for loss input data:

n_loss_sl n_loss_qo1 1

Two lines for empirical loss data:

i_qo_loss k_loss f_loss loss1 1 0.500 0.86

Two lines for deviation input data:



Appendices

n_dev_sl n_dev_qo1 1

Two lines for empirical deviation data:

i_qo_dev k_dev f_dev dev1 3 0.500 0.00

Two lines for blockage input data:

n_ewb_sl n_ewb_qo1 1

Two lines for empirical blockage data:

i_qo_ewb k_ewb f_ewb ewb1 1 0.500 0.00

EXAMPLE 2

The following example of a correlations data file is for a nine-stage radial compressor with a vaneless diffuserand a return channel downstream of each impeller except the ninth. The losses in this case are specified asa single polytropic efficiency for everything, and the blockage is zero. But for the deviation of the flow fromthe blade angle at the trailing edge it is sensible to use a slip factor of 100 for the impeller and a deviationangle for the stator vanes. In this case 0.0 is specified as the slip factor so the Wiesner slip factor is used,and 5.00° is specified for the return channel deviation angle. k_dev controls whether to use the slip factoror deviation, and i_qo specifies the calculating station at which the slip factor or deviation is applied. Asensible rule would be to make the value of i_qo equal to the number of the q-o at the trailing edge, butthe program can accept any value between the previous trailing edge and the current one. If there is avaned diffuser with a different deviation angle then an additional line with k_dev set to 1 would be neededbetween each impeller and return channel line.


Typical correlations file for multistage radial compressorEfficiency, slip factor in impeller, deviation in stators, no blockage18 September 2008





Two lines for empirical loss data:

i_qo_loss k_loss f_loss loss1 1 0.500 0.80



Lines for empirical deviation data:

i_qo_dev k_dev f_dev dev1 3 0.500 0.0045 1 0.500 5.0065 3 0.500 0.0


Vista TF

95 1 0.500 5.00115 3 0.500 0.0145 1 0.500 5.00165 3 0.500 0.0195 1 0.500 5.00215 3 0.500 0.0245 1 0.500 5.00265 3 0.500 0.0295 1 0.500 5.00315 3 0.500 0.0345 1 0.500 5.00365 3 0.500 0.0395 1 0.500 5.00415 3 0.500 0.0





EXAMPLE 3

The following example of a correlations data file is for a radial turbine stage with an inlet nozzle and animpeller. In the example shown, the losses are different for the two components. The deviation angle isspecified by use of the cosine rule for both components (k_dev = 5) but a correction to this (2.00°) is appliedin the rotor.


Typical correlations file for radial turbine stageEfficiency, deviation as mod to cosine rule and no blockage18 September 2008





Three lines for empirical loss data:

i_qo_loss k_loss f_loss loss1 1 0.500 0.8835 1 0.500 0.75




i_qo_dev k_dev f_dev dev1 5 0.500 0.0035 5 0.500 2.00




Appendices




EXAMPLE 4

In all of the above examples, a constant value of the empirical information is applied on all streamlines, soonly a single value is specified. An additional feature is that the program also allows this data to vary acrossthe span for each blade row. Then there would be an additional line for each fraction of the span. This isshown with regard to the losses, which specifies the efficiency at 0%, 25%, 50%, 75% and 100% of the span.


Radial compressor impeller with spanwise variation of etaEfficiency, slip factor for impeller with no blockage18 September 2008





Lines for empirical loss data:

i_qo_loss k_loss f_loss loss1 1 0.000 0.771 1 0.250 0.791 1 0.500 0.801 1 0.750 0.791 1 1.000 0.77




i_qo_dev k_dev f_dev dev1 3 0.500 0.00





EXAMPLE 5

The following example of a correlations data file shows the use of a blade oriented specification for theKacker Okapuu correlations for an axial turbine calculation. No blockage is specified.


Vista TF


Typical correlations file for axial turbine - no blockageKacker-Okapuu10 September 2008




n_loss_bladerow dummy1 1

Two lines for empirical deviation data (i_loss = 2):

i_blrow i_loss_type f_loss(1) f_loss(2) f_loss(3) f_loss(4) f_loss(5) f_loss(6)1 1 1.0 1.0 1.0 1.0 1.0 1.0


n_dev_bladerow dummy1 1


i_blrow i_dev_type f_dev(1) f_dev(2) f_dev(3) f_dev(4) f_dev(5) f_dev(6)1 1 0.0 0.0 0.0 0.0 0.0 0.0




i_qo k_ewb f_ewb ewb1 1 0.500 0.00

EXAMPLE 6

The following example of a correlations data file shows the use of a blade oriented specification for theMiller-Wright correlations for an axial compressor calculation.


Typical correlations file for multistage axial compressorMiller Wright Correlations10 September 2008




n_loss_bladerow dummy1 1

Two lines for empirical loss data (i_loss = 2):

i_blrow i_loss_type f_loss(1) f_loss(2) f_loss(3) f_loss(4) f_loss(5) f_loss(6)1 11 1.0 1.0 1.0 1.0 1.0 1.0



Appendices

Two lines for deviation input data (i_dev = 2):

n_dev_bladerow dummy1 1

Lines for empirical deviation data (i_dev = 2):

i_blrow i_dev_type f_dev(1) f_dev(2) f_dev(3) f_dev(4) f_dev(5) f_dev(6)1 11 0.0 0.0 0.0 0.0 0.0 0.0


n_ewb_bladerow dummy1 1


i_blrow i_ewb_type f_ewb(1) ... ... .... ... f_ewb(6)1 11 1.0 1.0 1.0 1.0 1.0 1.0

Appendix F: Troubleshooting

The Vista TF program and numerical method is extremely robust, especially in unchoked flows and whenrunning from an existing restart file. There should generally be no numerical problems with radial compressor,radial turbine, and radial pump calculations, which are the first applications for which the program has beenreleased. Nevertheless convergence problems and unexpected program errors can still occur. The mostcommon problems are format errors in the input data or numerical problems inherent to the streamlinecurvature method or associated with choking. The numerical errors can sometimes result in a failure of thesolution to converge or even a complete breakdown as the compiled program encounters a FORTRAN error,such as the square root of a negative number, or a floating point overflow. The most common of these aretrapped and reported by the program. It is hoped that all such errors can be removed in a later version. Thecompiler of course will report these errors, but this is not of much use to the user. The most likely cause ofsuch errors is a data error. The sections below outline typical problems and suggest solutions for these withsome advice on how to deal with input format and data errors.

If the solution converges to the user-specified level of convergence then the program exits normally witha value of 0 in the command line (CALL EXIT(0)). If the solution has not converged but the maximum numberof iterations has been reached, then a value of 1 is returned. If the program has identified some seriousdifficulty which has an appropriate trap, then the program exits with a negative return value and prints anappropriate error message. Only the most common errors have been supplied with a trap against such errors.If the program identifies a feature of the input data which it determines may lead to some difficulties (rota-tional direction, grid aspect ratio, inconsistent flow and speed data) it prints a warning to the screen andthe output file. This information may help to correct the data errors.

Some examples of warnings and error messages are as follows:

WARNING: Anti-clockwise rotation

Vista TF suspects that the first rotor blade is counter-rotating

Possible cures:

(a)Change value of i_flow to be negative (b) Change geometry from left-handed to right-handed or vice versa

WARNING: Wilkinson damping factor used Damping factor damp_sc reduced by Vista TF to value suggested by Wilkinson

WARNING: error increasing -relaxation factors reduced 5%


Vista TF

ERROR: Error noted in subroutine throughflow_manager

ERROR TYPE: error_max > 400%

ERROR PARAMETERS: -10 10 17 139 0 0

0.2100E+16 0.5600E+00 0.7250E+00 0.2905E+01 0.0000E+00

Problem: Near to choke on quasi-orthogonal: 17 on iteration: 139Inlet mass flow: 0.56000Local estimated choke mass flow: 0.72497Local effective relative Mach number: 2.90494Possible cures:

(a) Remove this q-o from domain (b) Check consistency of flow and speed

Input-output Errors

If the program fails to run at all, then this is usually a sign that some of the formatted input data is notcorrect (no empty lines where these were expected, or an empty line where data was expected, or similarformatting problems). The screen monitor information then says that the file has broken down in a particularinput subroutine; this provides a clue for identifying which file has an incorrect format. Most straightforwarderrors caused by new users or new cases are related to the data input files, which are fairly rigid with regardsto the lines of data and which do not accept an empty line where a line of data should be. No built-in con-sistency checks of the input data are made, so errors of this nature can easily occur, especially at the beginningof a completely new calculation. To help avoid this type of error, you can copy lines from similar existinginput files.

The program might report the name of the input file that contains an error. Should such errors happen, youshould examine the .hst file where the input data is recorded. From this, you can determine which file hasnot been correctly read or might have errors, and also which part of that file has been successfully read.

If the program reads all the input files, starts successfully but then fails before the iterations begin, then thisis often a problem related to the specified flow and speed conditions in the input data or the geometryspecification, and these should be checked. These errors are usually related to errors in the units of thespecified data (flow conditions, boundary conditions, geometry, empirical data, and so on). A typical usererror of this type is that the diameter is needed as a reference value for the size in the flow information(.aer), but the user specifies a radius because the coordinates in the geometry file (.geo) are radius values.Another common error with users is to specify the geometry in inches rather than meters. Another typicaluser error of this type is that the pressure is specified in bars whereas it is expected to be in N/m2. Othererrors may be related to the fact that the specified flow conditions imply choked flow or reverse flow. Auseful consistency check of the flow data is made where the following information is printed:

Vista TF: Axial compressor calculation--------------------------------------Estimated mean flow coefficient cm/u at first rotor inlet = 0.4567Estimated mean Mach number cm/a at first rotor inlet = 0.4426

These values may be used to identify if the mass flow, speed and other data have been specified sensibly,as typical values of these parameters for each type of machine will be known.

If the program runs, but breaks down after only a few iterations, then this can often be a sign that some ofthe input data is still not correct because the program is generally very reliable. Here the strategy is to reducethe value of the maximum number of iterations to a lower value than that at which the flow breaks down(reduce the value of the parameter max_it_main in file .con ), to rerun the case, and then to examine



Appendices

the results in the .hst and .out files. The errors are usually related to mistakes in the specified data (suchas flow conditions, boundary conditions, geometry, and empirical data) rather than mistakes in the numer-ical method, and these data problems can then often be identified from un-converged results or valuesprovided in the .hst , .txt and .out files. It can also be useful at this stage to examine the plot files ofthe initial geometry set up by the program, which is named test_prefix.txt or test_prefix.csv .This can often identify aspects of the geometry or flow data that are inconsistent.

If the program runs, but the results are extremely unexpected, such that a pump impeller or a compressorstator blade row has been interpreted by the program as a turbine row, then the blade angle definitionshould be checked. The program attempts to identify the type of blade row from the geometry specified,but in some cases the rules that have been programmed may fail. For example, a compressor stator isidentified as a stator blade row which turns the absolute flow towards the meridional direction, that is theblade angle decreases from the leading edge to the trailing edge through the blade row. In some specialcases, such as an axial compressor stator with a degree of reaction above 100% or rotor blades with extensivelocal leading edge recamber, the blade may have other blade forms. In these cases it is possible to specifyadditional data in the geometry file (see parameter i_row below) to overwrite the program’s own attemptsat blade type identification. Geometry produced by BladeEditor contains blade type information providedthat, in the blade feature within BladeEditor, a blade type (rotor or stator) is specified.

Convergence

The program has several different internal convergence checks, but a converged solution can be achievedonly if all of the internal loops also converge, so only one convergence criterion really needs to be checked,which is the convergence of the meridional velocity.

The most important convergence check is the maximum error of the local meridional velocity anywhere inthe flow field, expressed as a percentage of the local meridional velocity and denoted as error_cm (%)on the screen and in the output files. During the iteration process, the maximum value of the change in themeridional velocity in the whole flowfield between one iteration and the next (delta_cm % ) and the loc-ation of the maximum error is printed onto the screen every 10 iterations and into the history file for eachiteration. The local value of this error is also printed in the output file and into the .csv and .txt plotfiles. To achieve convergence near machine accuracy, use a maximum value of 0.01% as a convergence cri-terion. Note that this corresponds to a maximum residual error in CFD terminology of 0.0001, that is 1E-04,which is a much more stringent criterion than the RMS residual error often used in CFD programs of 1E-04.The value of the local error is output for examination with plot software and, for cases that have not con-verged, it is worthwhile to examine the location of the maximum as this may identify the location of theproblem.

It is important to remember, however, that numerical methods have many sources of error. In a throughflowcalculation, the so-called model errors, related to the fact that the equations we are solving do not reallydescribe the real flow particularly adequately (in this case we solve for inviscid, circumferentially-averagedmean values on widely spaced grid lines) probably outweigh all other sources of error. A solution that isconverged to a maximum error in meridional velocity of 0.5% is likely no worse in terms of its agreementwith reality than a solution that converges to 0.01% or lower. So calculations that converge to 0.5% can alsobe considered to be converged for practical engineering purposes.

The second convergence check occurs in the innermost mass-flow iteration loop where the program monitorsthe number of loops required to solve the continuity and radial equilibrium equations on each calculatingstation. The maximum value of the number of mass flow iterations and the location of the quasi-orthogonalwhere this occurred is also printed onto the screen and into the .hst file. You can specify the maximumnumber of loops for the internal mass-flow iteration loop with the max_it_mass parameter in the controlfile. The recommended value for this parameter is 10. Early in the run, the program usually stops the internalloops when the value of max_it_mass is reached. Later, as convergence is approached, less then 10 internal


Vista TF

loops are generally required. A typical converged solution may require only 1 or 2 internal loops. The errorin the mass flow should be tighter than that for the meridional velocity; a value of 0.001% is currently re-commended.

The third convergence check occurs in an iteration to a specified pressure ratio and is related to the conver-gence of the inlet mass flow to a final value and the convergence of the specified target pressures at thetrailing edges to a fixed value. These are written onto the output file as error_p and error_mass respect-ively. The same limit for the mass flow convergence is used as given above and the target pressure conver-gence is set internally within the program to be tighter than this. Experience shows that it is important insimulations to a specified pressure ratio to ensure that tight tolerances on these parameters are given, oth-erwise the program modifies the target pressures on the basis of inadequately converged data and divergencemay result.

In some cases with closely spaced calculating stations (high aspect ratio grid) it has been identified that,although the simulation converges to a relatively low level of the maximum error in the meridional velocityof 0.1% relatively quickly, it does not always continue to converge below this level of error. In these casesyou have several options. Firstly, it might be sensible to accept this level of convergence and continue tooptimize the geometry of the machine. In some cases, the simulation that is not perfectly converged mayindicate the existence of an unwanted flow feature as a cause of the poor convergence. Such features include:anything that creates a tendency for the flow to reverse direction; an extremely high curvature in the meri-dional channel; a poor grid. A second approach is to make use of other models that are built-in for thedamping factors within the program, by reducing the value of the streamline curvature damping factordamp_sc and the velocity level damping factor damp_vl . In some cases it may be helpful to reduce boththe value of damp_sc and damp_vl to smaller values than the standard values of 0.25 and 0.40.

The most common failure for the program to converge is related to difficulties in the streamline curvaturecalculation causing divergence of the maximum error in the meridional velocity distribution. If the programidentifies a trend for the results to start to diverge then it automatically decreases the damping factors toavoid divergence by causing more damping of the solution. If the errors continue to increase, then furtherreduction of the relaxation factors tends to freeze the unconverged iteration at the state where the problemwas identified so that there is at least no unexpected exit from the program even if the simulation does notconverge. Because of this feature it is not advisable simply to increase the number of iterations in the hopethat the simulation will converge. A better strategy is to calculate with a large number, say 2000 iterations,and if the simulation does not converge, restart the calculation from the restart file to reset the dampingfactors to sensible values. This strategy often works in difficult cases.

The numerical fix of reducing the damping factors when the error diverges is reported on the screen andin the history file. If this fix does not work, then the calculation of the streamline curvatures may ultimatelyfail, although this only occurs in simulations that have otherwise started to have serious numerical problems.The ultimate failure here tends to be an error in the subroutine pero , called from subroutine curvature ,or in subroutine parabola , called from subroutine streamlines . Both are, in themselves, generally robust.Subroutine pero is a modified interpolation routine along the lines of the so-called AKIMA splines. Thebreakdown is related to the numerical difficulty of calculating curvatures in a flow when the streamlines areno longer smooth and the spacing of the calculating planes is small. Subroutine "parabola" attempts to fita parabola through internal data in the program and is also robust until serious problems occur. These errorshave mostly been trapped such that an error message is printed and the program exits the calculationwithout breaking down.

In cases where such problems occur, it is often worthwhile simply to run the simulation again from the restartfile generated from an earlier unconverged simulation or with a different initial estimate of the flowfield(which is controlled through the initial value of cm_start in the control file), because starting from betterinitial conditions may clear the problem found in the initial calculation. In choked flows it is generally betterto start with a lower value of cm_start , as this will not be choked. If this does not work then again a



Appendices

useful strategy is to reduce the value of the maximum number of iterations to a lower value, say 200 (para-meter max_it_main in file .con ), and recalculate and examine the unconverged results. It may also helpto run the simulation repeatedly with a low limit on the maximum number of iterations because each suc-cessive run tends to get to a lower value of the maximum error. If this fails, it is useful to examine the .hstand .out files and plots of the unconverged results. These files and plots can be used to identify aspectsof the design that, when improved, allow convergence to be achieved.

The program also writes the values of the local error and the local choke ratio into the .txt file so it ispossible to examine this and quickly locate the location where the problems are occurring. A value of unityfor the choke ratio implies that the flow is choked and a value above unity indicates that the local massflow is above the choking mass flow of the streamtube. It may be necessary to have some fundamentalunderstanding of how the turbomachine operates in order to identify how to remove these problems. Furthercomments on choking are given in Choking (p. 142).

The program prints an error message if it reaches a state where the maximum change in meridional velocityfrom one iteration to the next is more than 400% and then it closes down the calculation. Should this occurit is then recommended that you repeat the calculation with the maximum number of iterations set at avalue lower than that where the program stopped (see the history of iterations in the output file) and thenexamine the results for this unconverged point. This can help you to identify the problem.

Reverse Flow

Another common failure mode for the program where it has difficulties converging is related to difficultiesin calculating reverse flow in the meridional plane; such flow is not possible with the streamline curvaturemethod. If the program observes that reverse flow occurs in the meridional plane, then it attempts temporaryfixes to enable the iterations to proceed in the hope that the problem will be cleared. One particularly im-portant fix (that is not reported) is to avoid negative values of the meridional velocity by setting any negativevalues to 5% of the mid-span value. This may be used in early iterations and later no longer be needed, butif the final “converged” result contains such values, it is not really a valid solution. This can often be identifiedby a difficulty in convergence at a particular location in the grid. The background to this problem is a fun-damental difficulty related to the physics, whereby a strongly swirling flow in an annular duct may separateat the hub or shroud, and the streamline curvature method is inherently unable to calculate such a reverseflow. This problem becomes more serious with calculations of low hub-to-tip ratio. The use of a limit on themeridional velocity on any streamline is reported in the output.

Choking

It should be mentioned that the throughflow method is not particularly suitable for choked blade rows becausethe mean stream surface equations average out the flow in the circumferential direction and are thereforenot aware of high Mach numbers on the suction surface of blades. In addition, any shocks that may bepresent in turbomachinery flows are generally not oriented in the circumferential direction so are smearedout in the circumferential averaging of the flow to determine the mean stream surface. Furthermore, thebasic method is inviscid and this precludes the existence of strong shocks.

Nevertheless, despite these serious limitations, an attempt has been made to model choking in the bladerows so that, in combination with correlations, the maximum flow and the additional losses related to shocksare taken into account in the overall predicted performance. In this way, the program includes aspects ofchoking that are compatible with the level of empiricism of typical 1D calculation methods, and may evenbe more successful than these because the variation of Mach number over the span is taken into account.This is useful in a program intended for design purposes because it helps choking problems to be identifiedat a relatively early stage in the design process, and aids the understanding of the axial and radial matchingof the blade rows as the rotational speed varies.


Vista TF

All aspects of special calculations for choking flows are hidden. Setting the parameter i_expert = 0causes the program to examine choking but not limit the mass flow if choking is found to occur. This is themost robust way to run the program and is recommended for beginners. Expert users can use i_expert= 1 , which limits the mass flow according to various choke models.

Choking is strongly related to the throat areas between two blade rows, so any real estimate of the chokingflow should make use of accurate estimates of the throat areas. In Vista TF the shortest straight-line distancebetween two blade rows can be specified in the geometry file for each of the input sections, and if the valuesare not specified (that is, a value of zero is given) then Vista TF makes its own crude estimate of the throatareas based on its limited knowledge of the blade geometry. This estimate is, at the moment, too crude tobe used accurately in the calculation of choked blade rows, and may lead to a value for the choked massflow that is incorrect. It may be worthwhile, in some situations, to run Vista TF with no values specified forthe throat and then examine the program´s own estimate of the throat areas, which are in the output file,and then run with slightly larger or smaller values specified in the geometry file, depending on the realthroat areas or the choking mass flow if the latter is known.

One method that tends to work in the most difficult cases is to remove any calculating planes in theneighbourhood of the throat, as suggested by Denton (1978). Local details of the flow calculation are lost,but the calculation can then be made to converge up to the limiting mass flow.

When you specify a mass flow rate, you must ensure that it is not greater than the choking value. The programmay generate warning messages if the specified mass flow exceeds the choking value.

The output parameter choke_ratio is the ratio of the local mass flux to the maximum possible at thatlocation. A value above unity is not a realistic solution but if the choke parameter i_expert is set to zerothen such solutions can be generated. This option is available because the program is sometimes more robustunder this operating mode than when i_choke is set to 1 and the full choking models are used. Note thatin some multistage computations the actual specified mass flow may be below that required to actuallychoke the machine, but during the iterations, individual blade rows may still become choked. The programbecomes less robust as choking is approached.

In some high-speed situations where it is difficult to obtain convergence with a specified mass flow, the restartfile can be used to store results for a converged operating point at a lower speed and lower flow, and thenthe required operating condition can be obtained by starting from the restart file with new flow conditionsslowly stepping to the required operating point. In a similar way, it is advisable to first set up a simulationclose to the design flow, before attempting to move towards a higher flow with a higher risk of choking.

You can run a simulation with a specified pressure ratio. For a choked blade row, the shift to a specifiedpressure ratio is a more physical approach than specifying the mass flow because, in this case, the solutionis indeterminate. In turbines with steep characteristics (little variation in mass flow with pressure ratio) thisis reliable. In compressors with flat operating characteristics (large variation in mass flow with pressure ratio)this approach may be more unstable so it is not recommended for calculations close to the expected surgeline.

Iteration to a defined pressure ratio makes use of the so-called “target pressure” ratio method of Denton(1978). This requires the program to make a first guess of the pressure at each trailing edge of the machine.The algorithm currently incorporated makes a crude estimate of this but it has been found that this maynot be sufficient to secure convergence, especially for compressors. For this reason, you have the option todefine the first guess of the pressure at each trailing edge (set i_flow = 6 instead of i_flow = 5 ).Even when using this option, the iteration to pressure ratio for multistage compressors is still very sensitive,and convergence is not guaranteed. If iteration to pressure ratio is used for choked blade rows, then an ac-curate estimate of the throat widths needs to be provided in the geometry file and the value of i_expert



Appendices

should be set to 1 so that the limits to the mass flow at choke are imposed. If the throat area feature iscalculated by BladeEditor then the throat widths will be calculated and added to the geometry file.

Computational Grid

As in most numerical methods, a finer grid leading to a closer spacing of the quasi-orthogonal lines andstreamlines will lead to a higher numerical accuracy of the simulation. Closer spacing of the quasi-orthogonallines for streamline curvature calculations can, however, cause instabilities in the convergence process. Thiscan be overcome by increasing the numerical damping (lowering the relaxation factors) but this causes anincrease in computational time, so a compromise is generally needed.

The relationship between the needed relaxation factors and the aspect ratio of the computational grid in athroughflow calculation was theoretically derived in a classical paper by Wilkinson in 1970 (see Streamline

Curvature Throughflow Theory (p. 118)). His studies showed that close spacing of the quasi-orthogonal linesrequired more damping. The problem is related to the fact that if the calculating stations are closer togetherthen a small displacement of a streamline can lead to a large curvature. In this case it is only possible totake a small part of the new solution forward each iteration and so the number of iterations increases.Wilkinson derived an equation of the following form to calculate the optimum relaxation factor for a certaingrid aspect ratio:

He also showed that the value given here as k2 is actually a function of the Mach number, the flow angle,and of the method used to calculate the curvature of the streamlines. The aspect ratio of the grid (h/∆m)in this equation is the ratio of the calculating station length to the meridional spacing of the grid lines. Theequation above was used in older versions of Vista TF to determine the streamline curvature relaxation factorwith the numerical values of k1 = 0.5 and k2 = 20/96. The value was based on the largest aspect ratio thatcan be found in the domain. This is then further reduced if the calculations show any tendency to divergeduring the iterations. The largest aspect ratio in the whole grid was used, whereby the meridional spacingis the shortest meridional distance between the two adjacent grid lines.

A value of 0.01 for this relaxation factor corresponds to an aspect ratio of around 15 and will lead to longcalculation times because only 1% of the new solution can be taken into account and 99% is carried forwardfrom the earlier solution. In order to reduce an error in the initial solution to 0.01% of its initial value thenthe number of iterations required would be

A value of 0.001 for this relaxation factor (aspect ratio near to 50) would lead to ten times as many iterations.Values of the aspect ratio larger than 15 are therefore not recommended but in cases where this is unavoidable(such as low aspect ratio blades with high span and small chord with internal calculating stations) then theprogram still converges but at a slower rate.

A different stability scheme has been incorporated in Vista TF. In this, the relaxation factor ratio is calculatedas:


Vista TF

Where alpha is the absolute flow angle in ducts and stator rows and the relative flow angle in rotor rows.In the new scheme, the relaxation factor can vary from quasi-orthogonal to quasi-orthogonal so that regionsof the grid with small aspect ratios are not penalized by a locally poor grid spacing elsewhere. In additionto this improvement, experience with many difficult cases has been incorporated in the selection of themaximum relaxation factor. With this new model, you should not need to adjust the damping factors becausethe program does this automatically.

All flow gradients in the radial equilibrium equation and the curvature of the streamlines in the solution aredetermined by a piecewise parabolic interpolation through three points. This is a very rapid numerical pro-cedure but experience shows that this can cause errors in the estimation of the curvature of the hub andcasing if the quasi-orthogonal spacing is too wide. For the case of an axial to radial bend with circular arcmeridional wall contours the error in curvature is of the order 2.5% on a grid with 7 quasi-orthogonal lines(a quasi-orthogonal placed every 15° around the bend). This decreases to 0.2% for 19 quasi-orthogonals (aquasi-orthogonal every 5°). This suggests that typical radial impellers with an axial inducer should be calculatedwith around 15 quasi-orthogonals in the bladed region. Moreover, the basic assumptions of the meridionalthroughflow method (for example: no frictional forces, axisymmetric flow, no spanwise mixing) certainlycause larger errors than this error in the curvature estimate.

It should be noted that decreasing the convergence tolerance to low values does not eradicate this error,so that for typical engineering applications a tolerance of 0.1% on cm is generally adequate because thecurvature calculation is not more accurate than this. A lower value is however generally used because thisconfirms that numerical convergence has really happened.

Using 17 streamlines across the span is recommended. The use of such a large number of streamlines acrossthe span brings little improvement in the accuracy when compared with experimental data compared tousing only 9, but nevertheless clearly leads to fewer numerical errors in the integration of the radial equilib-rium equation. 17 and 9 streamlines have the advantage that the streamlines split the flow uniformly into16 or 8 streamtubes.

The limitations mentioned above on the calculation of flow gradients and curvature also determine to whatextent details of steps in the wall geometry can be taken into account. Steps, kinks and wells in the meridi-onal contour need to be omitted as these features are typically of a sub-grid size. Generally attempts toimprove the accuracy by using finer grids with more details are not made in streamline curvature calculationsbecause this is counterproductive.

In axial turbomachinery calculations with quasi-orthogonals at the leading edge and trailing edge planesand with flare on the hub and casing walls, inaccuracies will arise because the kinks in the contours cannotbe accurately modeled.

Other Numerical Issues

Computing a new solution from the restart file of an existing solution, even when no changes have beenmade in the input data, generally requires 50 or more iterations to re-converge to the solution on the restartfile. This effect is due to the fact that the restart file stores only a small part of the information related tothe original solution, and many fine details of the solution have to be recalculated.

In running the program from a cold start (without a restart file) it is useful to think carefully about the initialvalue of cm_start that is specified for the control file. This determines the meridional velocity level of theinitial solution and it has been experienced that an initial value too far from reality may cause the solution



Appendices

to breakdown. The value that should be specified for cm_start is the flow coefficient (cm/u) of the machineconcerned, whereby the reference velocity used is the velocity determined by the reference diameter andreference speed (ref_d and ref_n ). In flows with a risk of choking, it is better to use a low value ofcm_start to ensure that the initial conditions are not close to choke. When a converged solution is availableas a restart file, it should be used because, although it does not necessarily reduce the number of iterationsneeded, it does make the solution process more robust.

The restart file is continually updated by each converged computation, but also if the solution reaches thelimit of the maximum number of iterations without converging. In a case where the solution is actually di-verging, the non-converged restart file might be a worse starting condition than the program´s own initialguess, so it can be useful to discard this and start again. If a converged solution has been reached then itis sometimes useful to store the converged restart file for a better starting solution if something later goeswrong during calculations at other operating points.

As with all numerical methods, the use of unconverged results for design decisions is extremely dangerousand is not recommended. Nevertheless, examination of unconverged results can often be extremely usefulfor identifying numerical issues. In some cases examination of unconverged results may indicate features ofthe design that can be changed to avoid such problems by modification of the geometry.

One measure that has been incorporated and which may be useful during debugging of a poor calculationis to set the parameter grad_ree equal to zero. This overrides the radial equilibrium equation and leadsto a spanwise constant meridional velocity (see below). This can be useful in identifying errors where flowdata is inconsistent with the geometry being calculated. Another alternative that can be used with turbinesis to specify a near-zero swirl velocity on the mid-streamline at the outlet of the last rotor and let the programdetermine the mass flow and pressure ratio consistent with this (“iteration to outlet swirl”). This has unfortu-nately not been thoroughly tested on enough cases to guarantee that it will always work.

If all else fails then set i_ree = 3 in the control file. Under these circumstances the value specified asgrad_ree in the control file is then used to reduce the meridional velocity gradient as follows:

This can be extremely useful for debugging, because it can allow the program to avoid failing due to highspanwise velocity gradients. In this way, it effectively becomes a mean-line program with no spanwise variationin meridional velocity (if grad_ree = 0.0 ). Other parameters such as the blade speed still vary acrossthe span, so it is not exactly a mean-line program. Most cases converge under these conditions and thisensures that the axial matching along the mean streamline of the blade rows is approximately correct. Whenconverged it may be possible to approach a solution with the correct radial distributions by slowly relaxingthe value of grad_ree towards unity. During this process, the features of the velocity gradients that causetrouble slowly become part of the calculation and this can then help to identify the problem.

Cases that do not converge well are usually either poor designs, or are good designs operating a long wayfrom their design point. Non-convergence generally means that the design is a long way from satisfying thecondition of radial equilibrium. If the flow solution converges well then this usually means that the flow isautomatically close to radial equilibrium and this will generally indicate a higher-quality machine.


Vista TF

Appendix G: The RTZTtoGEO Program

The ANSYS .rtzt and the Vista TF .geo Geometry Definition File

The data in the .rtzt file is the meanline coordinate data as produced by the program BladeGen on anumber of layers from hub to shroud, with a format as described in Description of the RTZT File (p. 150). Thereare several differences to the .rtzt option in BladeGen and the geometry actually needed by a throughflowprogram, and for this reason the RTZTtoGEO program has been written to convert this data into a moresuitable format, rather than working directly with the .rtzt file.

The first difference is related to the need for a throughflow program to work with blade angles, in the caseof Vista TF with the blade lean angles gamma_r and gamma_z (see Definition of Blade Lean Angles (p. 128)).Throughflow programs work on relatively coarse grids and so it is sensible to provide the programs withthe blade angles rather than just the blade coordinates. Otherwise the blade angles would have to be calcu-lated by interpolation and differentiation on a coarse grid which will lead to errors. In axial duct flow programswith planes just at the leading and trailing edges, this is done by specifying the axial blade angles or flowangles at the inlet and the outlet. In Vista TF, which includes the blade force in the solution and is designedfor radial machines, both the axial and the radial lean angles (gamma_r and gamma_z) have to be definedand, because the program includes internal planes, these are defined throughout the blade, not just at theedges.

The second key difference is that RTZT concentrates on the information required on each stream-surface (orlayer) at a certain percentage of the span of the blade, or on blade sections or layers. Throughflow programsconcentrate on the information in a plane at right angles to this and require information along equallyspaced quasi-orthogonal lines at fixed meridional positions through the blade rows, and upstream anddownstream. In .rtzt files, the number of points and spacing in the meridional direction is not the sameon each layer. In a throughflow program, it is the location of the layers on each quasi-orthogonal line thatmay be different, but the points along the streamline must be evenly spaced for all layers.

The throughflow program also needs additional data upstream and downstream of a blade row to definethe position of the quasi-orthogonal in a region of duct. This is not the case in the current .rtzt file, becausedifferent levels of information are available on each layer in this region, and curved quasi-orthogonals outsideof the bladed regions are difficult to define. In some of the cases tested with highly curved leading edges,it was necessary to modify the .geo file by hand to avoid problems with the quasi-orthogonals upstreamor downstream of the leading edge crossing the leading or trailing edge.

Conversion of a .rtzt File into a .geo File

A program, RTZTtoGEO, can be used to generate the geometrical input data file (file extension .geo ) forthe Vista TF streamline curvature program from the BladeGen RTZT output format (file extension .rtzt ).The RTZTtoGEO program can be obtained from PCA, although the preferred method to generate the .geofile is to use the BladeEditor VistaTFExport feature (see Export to Vista TF (.geo) (p. 46)). No guarantee canbe given that the RTZTtoGEO program will work on all cases. This program can be used to merge severalseparate .rtzt files from BladeGen into a single .geo file for multiple-blade-row simulations with VistaTF.

For a single blade row, the program makes use of three files:

• One input data file is needed: RTZT geometrical data file (.rtzt ).

• The program creates one output file: Vista TF geometrical data file (.geo ).

• The input and output file names are specified by you in an auxiliary data file that must be calledrtzt.fil . It must contain the necessary file names in the following order and form:



Conversion of a .rtzt File into a .geo File

Number of blade rows 1RTZT datafile name impeller.rtztVista TF geometry datafile name impeller.geo

For multiple blade rows, additional .rtzt files are needed for each blade row and the associated .geofiles are merged into a single .geo file for the whole domain. The number of individual blade rows is givenin the first line and the names of the individual .rtzt files follow this.

For n blade rows the program makes use of n+2 files:

• n input data files are needed: n RTZT geometrical data files (.rtzt ).

• The program creates one output file: Vista TF geometrical data file (.geo ).

• The input and output file names are specified by you in an auxiliary data file that must be calledrtzt.fil . It must contain the necessary filenames in the following order and form:

Number of blade rows nRTZT datafile name Prefix1.rtztRTZT datafile name Prefix2.rtzt: :RTZT datafile name Prefixn.rtztVista TF geometry datafile name impeller.geo

Note that the different .rtzt files must be generated from BladeGen files that join up to each other con-sistently with no gaps. If the domains between adjacent blade rows as defined by the .rtzt files meetexactly at the boundary of the domains then the program includes a single quasi-orthogonal at thisboundary.

Running the RTZTtoGEO Program

The file impeller.rtzt and the file rtztgeo.fil should be in the same directory as the executableof the compiled program files. Starting the program produces the .geo file from the .rtzt file. If the .geofile already exists, there is a prompt as to whether this should be overwritten.

The program prompts you to identify whether the blade row is a compressor (pump) or turbine, andwhether it is a rotor or stator. In addition the program suggests the number of quasi-orthogonals upstreamof the leading edge and downstream of the trailing edge but you can change these numbers if this seemsappropriate, simply by replying with n (n = “no”) to the prompt and then suggesting the new number ofquasi-orthogonals to be used. If you reply with a y (y= “yes”) then the automatic choice of the program isused, which is fairly sensible in most cases.

Note

The limit on the number of points in each layer of the .rtzt files is 1000. The limit on thenumber of layers is 15. The maximum number of blade rows is 20. Up to 3000 quasi-orthogonalscan be included in the final .geo file.

There are options to modify the number of quasi-orthogonals in the blade row and to change the orientationof the calculating grid so that this is oriented in the positive z direction. The change in orientation is neededbecause in some BladeGen files the flow travels in the direction of the negative z axis, and Vista TF assumesthat the flow is traveling in the direction of the positive x axis. Without this switch the hub and shroudcontours become reversed. The option to modify the number of quasi-orthogonals in a blade row has been


Vista TF

included so that RTZTtoGEO can better cope with axial blades with short chords relative to radial machineswith long chords. The program makes its own choice of the number of quasi-orthogonals needed, basedon the aspect ratio of the blade; this is more or less consistent with the stability requirements of the VistaTF program. The rule used leads to 16 quasi-orthogonals in most radial compressors. You can change thisnumber if this seems appropriate, simply by replying with n (n = “no”) to the prompt and then suggestingthe new number of quasi-orthogonals to be used. If you reply with a y (y= “yes”) then the automatic choiceof the program is used, which is fairly sensible in most cases.

Merging Several .rtzt Files into a Single .geo File

Vista TF can run a computation for up to 20 blade rows. BladeGen can currently only be used to define theblade rows individually so each .rtzt file contains only a single blade row. It is possible to merge theseinto a single .geo file automatically using Vista RTZTtoGEO, as explained above. The procedure below de-scribes how to merge individual .geo files by hand, just in case the automatic option fails.

1. Run RTZTtoGEO for the first blade row.

2. Set up a Vista TF calculation for this blade row with all the appropriate input files and get this toconverge.

3. Run RTZTtoGEO for the next blade row.

4. Edit the .geo file of the first blade row to include the additional information for the downstreamblade row, as follows:

1. Change the title section as appropriate (section 1).

2. Add new quasi-orthogonals in section 3 (copy from the .geo file of the next blade row and addto the .geo file of the first blade row). This may require modifications by hand in the duct regionbetween the blade rows because the quasi-orthogonals have to step smoothly from inlet to outletand not overlap. Usually this means deleting some quasi-orthogonals downstream of the firstblade row and upstream of following blade row where the domains would overlap. Note that thenumbering of the quasi-orthogonals does not have to be changed because the program does notread this information. The numbering of each quasi-orthogonal can then be left as originallyoutput by the RTZTtoGEO program. Be careful in this process not to add any extra empty lines tothe .geo file between the different lines or to take any away. Note that the type and orientationof the blade row should be correct automatically (with i_type 2 for stators and 3 for rotors) andthat the number of upstream and downstream quasi-orthogonals can be modified so that thisprocess is easier.

3. Do the same for the blade definition section (section 4), whereby only those lines within the bladerow need to be copied in.

4. At the end of the .geo file, the details in section 5 need to be modified to give throat areas forthe blade row that has been added (which is actually zero because the ,rtzt file does not providethis information. Thus if there are two blade rows each defined with five sections then there wouldbe 10 lines at the end of the .geo file. These extra lines can also be cut and pasted from the.geo files for the appropriate blade row if you want.

5. Count the number of quasi-orthogonals that are left and change this in section 2. If you are luckyand have not had to delete any quasi-orthogonals, this is straightforward.

5. Edit the .cor file of the first blade row to include additional downstream blade row losses, deviation,and blockage data, noting that the location of the deviation is related to the number of the quasi-or-



Merging Several .rtzt Files into a Single .geo File

thogonal and not the blade row. Note that the aerodynamic and control data files (.aer and .con )do not usually need to be changed in this process.

6. Delete the restart .rst file because the restart capability only works if there has been no change tothe number of quasi-orthogonals. Vista TF recognizes this and recreates a new restart file automatically.

7. Run Vista TF, and repeat from step 3 for each additional blade row. Note that experienced users mightmanage to make the modifications to the .geo file and the .cor file for several blade rows togetherin 1 step, but doing it step-by-step gives better control of where any errors have been introduced.

Description of the RTZT File

This section describes the generic RTZT data file format for BladeGen. The file is an ASCII file that uses spaceseparation between values.

Note

Angular values must be in radians.

Example file:

text enclosed in {} is a data itemtext enclosed in () is a commenttext enclosed in [] is optional

{number of blades}{number of splitters} (0 is main blade only)(for each blade, main and splitter) {pitch fraction} (Ignored for main blade) {number of layers} [N] [T] (Normal or Tangential Thickness Flag)

(for each layer) {span fraction} {number of points} [a][t][b] (for each point)

{r} {theta} {z} {thickness} : :


Vista TF

Index



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