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Flow Analysis of Industrial Equipment using the native OpenFOAM GUI HELYX Dutch OpenFOAM® Users Group – 6th user meeting
September 17th, 2013
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Agenda
Introduction HELYX: Improved OpenFOAM® version with GUI HELYX-MESH: Mesh enhancements Case 1: Analysis of a pump suction line Case 2: Analysis of an actuated butterfly valve Final words
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Profile Dynaflow Research Group (DRG)
Engineering consultant Pipe stress calculations Stress calculations in vessels, heat exchangers, other equipment Transient pipe flow calculations Since 5 years increasingly CFD (either directly or within project scope)
Clients mostly Oil and Gas industry Benefits of OpenFOAM Cheaper than commercial CFD (HELYX 11,500 EUR annual fee) Low additional parallelization Access to source code
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Challenges using OpenFOAM® solved by using HELYX
Clients have doubts about using OpenFOAM® compared to commercial CFD Mostly ignorance at the client results in concerns about reliability of results Solved by an alliance with ENGYS to use and act as a reseller of HELYX CFD
Meshing Robustness Quality in complex industrial geometries Fast and reliable meshing allows faster project handling
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Agenda
Introduction HELYX: Improved OpenFOAM® version with GUI HELYX-MESH: Mesh enhancements Case 1: Analysis of a pump suction line Case 2: Analysis of an actuated butterfly valve Final words
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What exactly is HELYX CFD?
HELYX-GUI: Propriety Native GUI tailored for the HELYX-CORE.
HELYX-MESH: Improved version of snappyHexMesh leading to much better layer
generation, faster mesh generation times (up to 50%) and faster convergence (up to 30%) compared to the standard OpenFOAM® mesher.
HELYX-CORE: Extended OpenFOAM® library with many improvements originating from industrial projects.
HELYX-CORE Documentation: Extensive documentation (500+ pages) of the HELYX-CORE, including detailed description of all standard OpenFOAM® modules.
Unlimited 1st Class Support: Telephone/email help line.
Simple, single file installer: Installers available for Linux and Windows platforms.
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Significant enhancement based on industrial projects (I)
Based on OPENFOAM® 2.1 (2.2 integration Q3 2013) Full integration of Engys Edition enhanced features Instant updates with online repository Support for ParaView with parallel cases Single file caseSetup for batch execution Multiphase Arbitrary mesh interfaces User customisable modules for a large range of solvers
Improved, fully integrated radiation (thermal and solar) Humidity transport with wall evaporation/condensation swak4Foam integration
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Significant enhancement based on industrial projects (II)
General solver support for porous-thermal-MRF zones 50+ new boundary conditions Improved wall functions and simplified turbulent inlets 0D lumped capacitance transient thermal boundaries Resistive outlet
Coupling with RadTherm, a professional thermal simulation tool Accelerated Conjugate Heat Transfer (CHT) analysis Improved solver stability (DES, multiphase) Run time output of Ensight data Enhanced meshing
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Agenda
Introduction HELYX: Improved OpenFOAM® version with GUI HELYX-MESH: Mesh enhancements Case 1: Analysis of a pump suction line Case 2: Analysis of an actuated butterfly valve Final words
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HELYX-Mesh overview: comparison with OF 2.2.0 Feature HELYX snappyHexMesh 2.2.0 snappyHexMesh
Automatic blockMesh
Feature Line (Automatic and Implicit) (Manual and Explicit)
Searchable surface feature Lines
Multi-region support
Non-manifold splitting (robustness) Edge collapsing
Proximity refinement
Volumetric smoothing
Parallel (scaling above 60 cores) (no scaling above 60 cores)
Layer control (10 different methods available) (3 different methods available)
Small leak closure
Wrapping
Interior Layers
Automatic AMI setup
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Automatic feature edge capturing (no need .eMesh) Improved surface snapping and full projection of near-wall layers to inlets, outlet, symmetry planes
Standard v2.2 HELYX 2.1
Comparison snappyHexMesh (searchableCylinder)
Standard v2.2
HELYX v2.1
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Extended boundary layer control
N 10 R 1.3 T0 1mm
N 5 R 1.3 Tf 0.4
T 2 tf 0.3 t0 1mm Specify any three of the following
parameters: First cell height (t0) Final cell height (tf) Expansion ratio (R) Number of layers (N) Total layer thickness (T)
Improved handling of high aspect ratio elements
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Enhanced layering on concave and convex edges Important for resolving boundary layer flows for internal/external flows
Standard v2.2 HELYX 2.1
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Internal boundaries and virtual surfaces
Layers on internal boundaries and virtual surfaces
CHT / FSI mesh generation Improved interior boundary capturing Interior feature lines 2 sided layer generation
Virtual surface layer generation for wakes and mixing layers Specification using tri-surface (STL files)
or a defined primitive shape
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Small leak and crack detection in geometry Closing the user-defined tolerance
Automatic repair of gaps in the CAD generated surface
Increases usability and robustness for complex industrial cases
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Automatic wrapping of mesh around geometry Missing geometry and big holes will be fixed
A gap lead to internal meshing Automatic wrapping
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Example benchmark
HELYX Mesh 50% faster than standard snappyHexMesh
Solution 30% faster than on standard snappyHexMesh
Near wall layers: 97% coverage (95.7% from standard 2.2.x version)
1.7M cells
improved scaling on 32+ processors
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Agenda
Introduction HELYX: Improved OpenFOAM® version with GUI HELYX-MESH: Mesh enhancements Case 1: Analysis of a pump suction line Case 2: Analysis of an actuated butterfly valve Final words
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B
C
B
Layout suggested by client Layout required by pump manufacturer
In field no space to fit extra pipe section
Pump suction nozzle
Problem description 5D straight section required by pump manufacturer to obtain flat flow profile
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Problem breakdown and approach Short project duration ~ 3 weeks (typical)
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Inlet side
Gate valve
Filter unit
Setup models in HELYX (short, with 5D, with(out) filter)
Mesher: HELYX snappyHexMesh
Solver: laminar simpleFoam /
pimpleFoam
Analyse results in paraView − Qualitative analysis of flow patern − Quantitative analysis of pump
entry flow
Pump suction nozzle
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System overview; pump suction line
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Inlet side
Gate valve
Filter unit
Pump suction nozzle
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Naming the case and setting parallel run options
Automatic decomposition
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Selecting multiple .stl files to define geometry/features
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Defining surface refinement levels on the patches Possibility to set levels of multiple patches simultaneously
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Defining volume refinement regions Using primitives or .stl files
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Selecting .stl files to define detailed filter zones
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Naming the cell zones and specify refinement levels Each cell zone can independently be refined
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Setting the inside point and Create Mesh snappyHexMesh includes an automatic blockMesh functionality
snappyHexMeshDict
snappyHexMesh runs automatically
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Setting up solver parameters after mesh generation
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Defining the fluid properties Possible to append an user fluid to the database
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Specify boundary conditions on the different patches Intuitive boundary conditions based on best practices
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Define the porous media on the cell zones Cell zones generated in meshing phase
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Start the simulation All initial conditions in dictionary files are generated automatically
Case structure is setup
solver runs automatically
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Meshing at zone edges has steadily improved in OF HELYX appears to be more robust concerning surface snapping
OF 2.2.x – edge snapping OF 2.2.x OF 2.1.x HELYX
2.2.x has clearly improved meshing on zone edges
2.2.x less robust at surface snapping
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Feature edge snapping has been incorporated in OF 2.2 HELYX performs more reliable in feature edge snapping without use of .eMesh
OF 2.2.x – edge snapping HELYX
Edge snapping has been improved , However is not as robust as in HELYX
OF 2.2.x
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OF 2.2.x Feature edge snapping is very sensitive to number of snapping iterations
OF 2.2.x – edge snapping; n=3 OF 2.2.x – edge snapping; n=2
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HELYX results in smoother and more homogeneous refinement
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HELYX – snappyHexMesh OF 2.2.x – with edge snapping
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HELYX refines consistently at sensible locations
HELYX OF 2.2.x – with edge snapping
Red lines are the zone edges
Irregular refinement around zone edges
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HELYX reliably makes the defined zones
HELYX OF 2.2.x – two zones have failed
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HELYX results in a smoother zone surface
HELYX – smooth zone surface OF 2.2.x – more castellated surface
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Results, qualitative
Pressure drop results in flow perpendicular to the filter surface
Two vortex structures are found in the filter’s downstream flow
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Results, quantitative Each quadrant may not deviate by more than 8% from the cross-sectional mean, this ensures acceptable balancing conditions inside the vanes of the pump’s impeller
2 3
4 1
Filter, with pipe extension No filter Filter
OK FAIL Just OK
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Problem solution as discussed and approved with client
Original filter design New filter design
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Agenda
Introduction HELYX: Improved OpenFOAM® version with GUI HELYX-MESH: Mesh enhancements Case 1: Analysis of a pump suction line Case 2: Analysis of an actuated butterfly valve Final words
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Problem description
Investigation of transient fluid-dynamic forces on actuated butterfly valve during closing Valve loading can cause problems for actuator Steady state investigation revealed no excessive flow
induced forces upon valve
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Problem summary
HELYX • transient, incompressible, moving
mesh (pimpleDyMFoam), automatic AMI setup
• Moving mesh + sliding interface • Dt=0.001 .. 0.002 (variable) • Simulated time T=20s ≡ 90°
valve rotation • K-omega SST model
Material: water
Two different cases:
• Variable flow – (nominal volume flow ~700m³/h)
• Fixed flow – (high flow case 2600m³/h)
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Transient simulation of closing valve Run time: 120 hrs / 12 cpus
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Variable Flow Case
Shedding induced vibration
Case: Fixed pressure loss
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Case: Fixed High Flow Rate
Within spread of straight pipe valve measurements
Greater flow bleed due to lack of valve seat
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Conclusions
Transient results agree well with steady CFD results and literature references No excessive forces on valve could be observed
Actuator problems likely caused by mechanical influences
HELYX successfully employed to mesh and run transient moving mesh simulation
AMI + dynamic mesh performs very well with minimal artefacts at the interface
Partial overlap AMI required for full closure of valve
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Agenda
Introduction HELYX: Improved OpenFOAM® version with GUI HELYX-MESH: Mesh enhancements Case 1: Analysis of a pump suction line Case 2: Analysis of an actuated butterfly valve Final words
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The strategic alliance with ENGYS gives DRG the opportunity to: Help our clients by doing CFD themselves using OpenFOAM® and HELYX
Using HELYX to improve our efficiency on CFD projects Provide and sell support packages including HELYX Supply training courses in HELYX and OpenFOAM® (November 25 & 26, 2013)
Use of HELYX allows DRG to: Reliably meshing of complex geometries
Fast setup of cases
Opportunities for you: HELYX: with GUI, MESH and CORE (to move from commercial CFD) HELYX-OS: GPL GUI tailored for standard OpenFOAM® instead of HELYX-CORE (to
occasionally solve CFD problems) HELYX-MESH: Stand-alone version of the HELYX mesh generator
Final words
T +31 79 361 5150 F +31 79 361 5149 E [email protected] W www.dynaflow.com
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