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Complete end-to-end workflow in a single integrated environmentANSYS TurboSystem provides a complete end-to-end workflow with the best tools and capabilities for every stage in the rotating machinery design process: quickly generating an initial design; creating and editing full 3-D geometry of rotating assemblies as well as ancillary components; fast 2-D blade throughflow simulation for rapid screening; and 3-D computational fluid dynamics (CFD) meshing and analysis delivered by steady-state, full wheel transient and partial wheel models. These tools enable engineers to predict turbomachinery performance to higher levels of fidelity, making it possible to optimize designs and solve problems in less time and with higher levels of confidence than ever before.

Application Brief

Rotating Machinery: A Critical CFD App You Have to Get Right

Rotating machinery such as compressors, turbines, pumps, fans, blowers, turbochargers, turbopumps, etc., play a central role in transportation, power generation, water supply and sanitation, energy supply and many other industries. Optimizing the design of the simplest to the most complex rotating machinery provides the potential for enormous savings. For ex-ample, each 1 percent increase in efficiency could save $66 billion in the gas-powered electri-cal generating industry or $30 billion in air transport over 15 years. But efficiency is just one of many challenges facing rotating machinery designers who are under pressure to improve all aspects of performance including safety, operating range, reliability, initial and operating cost, time to market, etc. The easy gains have already been taken — to get to the next level, rotating machinery designers need to build, test and verify their advanced systems in a cost-effective and low-risk virtual world before investing time and money in prototypes and physical testing. This application brief will explain how accurate simulation of rotating machinery can enable your engineering team to quickly evaluate alternative turbomachinery design iterations to in-crease efficiency, reliability and durability, and reduce emissions in a competitive, time-critical environment. Rotating machinery is a critical CFD app that you have to get right.

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You can proceed through the complete rotating machinery design process with an integrated set of tools in a single user environment.

ANSYS TurboSystem rotating machinery toolset is a full suite of design and flow analysis tools that are all seamlessly integrated into the ANSYS Workbench simulation platform. This streamlined approach reduces both engineering effort and time to market by eliminating the need to move or duplicate geometry, meshing and physical parameter information from one environment to another. An innovative project schematic view ties together the entire simulation process, guiding you through even complex multi-physics analyses with drag-and-drop simplicity.

Watch the ANSYS TurboSystem in Action: These short videos — Part 1 and Part 2 — show how a single integrated environment simplifies the rotat-ing machinery design process, in this case for the design and analysis of a pump impeller.


Quickly generate an initial design (ANSYS Vista CCD)

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Quickly generate initial design iterationsThe ANSYS TurboSystem provides a full spectrum of tools for simula-tion and design optimization of virtually any type of rotating machinery. At the beginning of the design process, engineers can quickly generate initial designs for further analysis using sizing tools specially designed for centrifugal compressors, radial turbines, centrifugal pumps and axial fans. Given the machine duty — mass flow, pressure ratio, etc. — and geometric constraints, these programs will generate the initial 3-D blade geometry and provide essential non-dimensional performance parameters, includ-ing specific speed and specific flow. The initial blade geometry is output directly for use in detailed modeling.

Interactively generate full 3-D designWorking with initial blade geometry designs generated in 1-D sizing tools or third-party tools, you can use 2-D sketches, either at span-wise or at us-er-defined positions, to immediately and interactively generate the full 3-D design. You can also generate quantitative information such as blade angles and throat area with ANSYS BladeModeler. Complete 3-D geometry model-ing capabilities make it easy to add any number of geometric features, such as hub metal, blade fillets, cut-offs and trims, or to combine blade designs with other non-bladed components, like housings, blade roots or complex 3-D tip regions.


Easily create turbomachinery-specific geometry using ANSYS BladeModeler that would be difficult and time-consuming with a generic modeling tool .

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Generate quick 2-D performance predictions You can perform rapid initial analysis of rotating machinery before pro-ceeding to more rigorous and detailed 3-D fluid flow simulations. The AN-SYS Vista TF 2-D throughflow solver evaluates a simplified set of equations on a 2-D meridional surface, with empirical correlations for loss, incidence, etc., so it can provide results in a matter of seconds or minutes. This rapid turnaround time makes it possible to rapidly improve the basic design early in the development cycle.

High-fidelity 3-D CFD simulation helps optimize the design prior to prototypingAfter you feel comfortable with the initial design, it’s time to perform detailed analysis to optimize its performance. ANSYS TurboGrid provides rotating machinery designers and analysts with mesh creation tailored specifically to the needs of bladed geometries. It creates high-quality hexa-hedral meshes for even the most complex blade shapes with the high level of mesh quality required to achieve accurate results in simulating rotating machinery. You simply define the desired mesh size and all the other steps are performed automatically. ANSYS’ meshing solutions deliver the right type of mesh with the right number of elements in the right place to ensure accurate and fast simulation.

Generate fast 2-D solutions that correlate well with higher-fidelity 3-D results (ANSYS Vista TF).

Quickly generate rotating machinery meshes for CFD simulation (ANSYS TurboGrid).


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Over two decades of experience in rotating machinery simulation, ANSYS has developed the physical models and infrastructure for accurate, robust and efficient modeling of a diverse range of rotating machinery. The ANSYS CFD toolset includes steady-state CFD, full-wheel transient CFD, an array of pitch-change methods and the new Harmonic Analysis (HA) method.

Due to its high levels of accuracy and computational efficiency, steady-state a multistage CFD method— is the approach of choice for predicting basic machine performance parameters such as mass flow, pressure ratio, work, power, efficiency and others. Users have the option of several different methods to simulate the interaction of rotating and stationary parts, based on the assumption of quasi-steady flow around the rotating component at every rotation angle. The Frozen Rotor model changes the frame of refer-ence or pitch, but the relative orientation of the components across the interface is fixed. The Mixing Plane model, also known as the Stage model, assumes the rotating and stationary components are fixed relative to each other, and performs a circumferential averaging of the fluxes through bands on the interface.

Transient simulation is needed whenever there is a close coupling of the flow between the blade rows, the blades are highly loaded or there are strong aerodynamic interactions between the rows. The transient rotor–sta-tor capability of ANSYS CFX resolves the true transient interaction between components for maximum accuracy. It can be applied to individual pairs of blade passages or to the entire 360-degree machine. However, transient simulation of turbomachinery flows is expensive and often time-prohibitive. It usually requires the simulation of the full-wheel geometry to account for the pitch-change between the blade row to accurately capture all the transient interactions. Accelerating transient rotating machinery simulationsOne way to reduce the computational effort involved in transient simula-tion is to solve the flow problem for a small sector of the machine — a partial wheel model. However, real turbomachines do not have an equal number of blades in each row so in this situation there is a pitch-change between the passages from one row to the next. The flow pattern will also repeat at the periodic boundaries of the passages, but it will do so with a phase-shift or a phase-lag between periodic boundaries. Transient blade row (TBR) interaction models can be used to model the interaction be-tween components in which the number of blades is unequal, causing the pitch-wise extent of the geometrically periodic blade passages to also be unequal. This powerful set of models greatly speeds solution times by 10x and even 100x with reduced-memory requirement compared to transient simulations of the full blade rows. The pitch-change or phase-shift in the reduced geometry simulations is accounted for by using one of three transformation methods: the Profile Transformation (PT) method, Time Transformation (TT) method or the Fourier Transformation (FT) method. The new Harmonic Analysis (HA) method performs flutter analysis in a hybrid time-frequency domain, achieving a computational speedup of 100X compared to a full-wheel solution.

Get the highest possible fidelity for rotating machinery simulation (ANSYS CFX).

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Optimized wastewater treatment compressor delivers 2 to 5 percent increase in efficiency Continental Industrie utilized the ANSYS TurboSystem to optimize the design of its newest single-stage centrifugal compressor for the wastewater treatment industry. Engineers used the ANSYS Vista CCD tool to perform preliminary design and sizing of the impeller and Vista TF to evaluate the 2-D blade row design. Next, they integrated the impeller into a complete 3-D compressor design and used ANSYS CFX software to simulate its per-formance. ANSYS DesignXplorer evaluated 250 designs to minimize flow losses through the volute. Engineers also used ANSYS Workbench to link the pressure and temperature predictions from ANSYS CFD to ANSYS Mechanical to evaluate the stress levels and deformation of the impeller wheel and other mechanical components. By using an integrated design process that optimized the compressor at three separate stages, Continental Industrie engineers delivered 2 to 5 percent higher efficiency than the company’s previous generation of wastewater aeration centrifugal compressors.

3-D flow simulation enabled Continental Industrie engineers to deliver a 2 to 5 percent improvement in efficiency in a compressor designed for wastewater treatment operations

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Efficiency of hydraulic pump increased 1–2 percent while reducing design time 30 percentGrundfos engineers used an in-house automated chain of simulation tools called Pumpit to drive ANSYS CFD software to optimize the hydraulic surfaces of a new pump design. They used design of experiments (DOE) to create a series of iterations that explored the design space for each component. PumpIt generated the geometry for each design iteration and issued a call to the CFD software to simulate each iteration. After optimiz-ing the hydraulic design with CFD, Grundfos engineers performed structural analysis with ANSYS Mechanical to ensure that each component meets fatigue life requirements while keeping cost and weight as low as possible. This approach made it possible to increase the hydraulic efficiency of the pump by 1 to 2 percent while extending the maximum efficiency level over a

Simulation enabled Grundfos engineers to increase the efficiency of a hydraulic pump by 1 to 2 percent.


The initial design of this tidal current power generator was limited because it produced so much turbulent kinetic energy (left). Using ANSYS CFD, engineers optimized the final design to generate power much more efficiently (right).

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wider range of flow rates. Compared to a traditional prototype-based design process, simulation reduced overall design time for the new pump design by 30 percent and saved approximately $400,000 in physical prototyping costs.

Tidal current generator optimized in 96 percent less time than previous methodsGilmore Engineers Pty Ltd was contracted to optimize the design of a new generation of tidal current power generators in which the outer diameter of the rotor blades is connected to the shroud to reduce the stress on the blades. Gilmore Engineers used ANSYS CFD software to simulate about 30 sizes and shapes of the shroud in a week, focusing on the diffusor or draft tube region, to determine the design that provided the lowest pressure while maintaining flow attachment to the wall. Further analysis was then performed on the best-performing shapes by varying the size, shape and number of slots and taking into account production costs. Engineers then simulated the blades in steady-state mode using the ANSYS CFD frozen rotor model to connect the rotating components to the optimized shroud de-sign. The design optimized by CFD generated 3,892 watts, an improvement of nearly 150 percent over the initial design. The complete design optimi-zation took 96 percent less time than would have been required using the build-and-test method.

Engineers achieve more accurate solutions with ANSYS TurboSystemDesigners of rotating machinery are under pressure to improve all aspects of their products’ performance including efficiency, reliability, operating range, initial investment and maintenance cost. To accomplish these goals, engineers need the ability to predict performance across an increasingly wide range of speeds and operating conditions while ensuring the reli-ability of the designs. ANSYS is continually advancing its core CFD solver capabilities as well as its special rotating machinery toolset to deliver the solution fidelity, robustness, usability, speed and optimization capabili-ties required to address the most difficult design challenges. The complete


Predicted impeller relative Mach contours for the rear stage of a gas turbine at 100 percent design flow at 95 percent span

Validation results show that ANSYS CFX accurately predicted performance parameters of the rear stage of a gas turbine.

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ANSYS TurboSystem is continually validated and re-validated to ensure that it solves the right equations while minimizing numerical, modeling and systematic errors.

ANSYS CFD was used in a validation case to analyze the moderate pressure ratio rear-stage centrifugal for an aero-engine gas turbine application in parallel with experimental mapping of the centrifugal stage in the Pratt & Whitney Canada Centrifugal Compressor Rig facility. The stage was modeled in steady state using a mixing-plane interface, and complete performance characteristics were predicted at the design speed using both K-epsilon and Shear Stress Transport (SST) turbulence models. At the design flow, the SST predicted efficiency was approximately 0.37 percent higher than the ex-periment results, and the predicted pressure ratio was 0.76 percent higher using the SST model. The SST choking mass flow was predicted within 1.09 percent. Overall, the simulation results agreed well with the measured data.

High-Performance Computing (HPC) enables large, high-fidelity models to be solved Design of rotating machinery is by its very nature a more complicated task than standard product design that requires more geometrical details and more complex physical models to explore how various design alterna-tives will behave across a range of real-world operating conditions. ANSYS High-Performance Computing (HPC) adds tremendous value to rotating machinery simulation by enabling engineers to evaluate larger, higher fidelity models with more complex physics at computational times that en-able them to add value at every stage of the product development process. ANSYS optimizes the entire HPC workflow by providing a unified environ-ment — across solver components — for defining, submitting and monitor-ing parallel workloads.

Validation case confirms that results for normalized total-to-static stage pressure ratio vs inlet and exit corrected flows match physical measurements.

ANSYS experts will transfer their knowledge and experience to youANSYS experts from the ANSYS Customer Excellence (ACE) team are dedi-cated to helping you get the most from our advanced technology solutions. The ACE team includes over 450 Ph.D.s who have seen and solved a vast array of engineering simulation problems, so they are well-equipped to help you overcome whatever challenges you are facing. An ANSYS Mentor-ing Expert will work with you on a short-term basis to coach you on how to optimize simulations to ensure accurate results that match your product. The ANSYS Learning Hub provides an easy way to access a broad range of courses and other resources that cover most types of simulation targeted at improving your team’s ability to make more effective use of simulation.

Accurate simulation can help you design better rotating machineryIn today’s globally competitive marketplace, it’s very difficult to imagine developing a competitive rotating machinery product without the benefit of simulation. Many rotating machinery companies were early adopters of simulation and played a significant role in shaping software development to their needs and validating it for their applications. The unequalled depth and unparalleled breadth of the ANSYS TurboSystem enables engineers to identify, diagnose and overcome even the most complex design problems in order to maximize efficiency and other performance parameters. ANSYS has developed specialized software with a vast array of physical models that enables engineering teams to predict rotating machinery performance and solve product design challenges faster than ever, with a higher level of confidence. Even the most complex design problems can be illuminated and addressed at an exacting level, enabling engineers to make ongoing im-provements that balance efficiency gains with other critical design criteria.


Recent improvements in parallel scalability for a 4-million-cell model in ANSYS CFD

ANSYS experts are well-equipped to help you overcome rotating machinery design challenges

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