Making Every RPM Count with Fidelity CFD

The growing complexity of industrial and turbomachinery equipment, such as compressors, pumps, turbines, and mixers, demands a change in the design methodologies to meet the challenges of uncommon or complicated geometries and operational environments. Today, engineers are tasked with creating high-performance machinery under tight deadlines, relying more on computational fluid dynamics (CFD) simulations to analyze flow physics and achieve better results faster.

As the need for miniaturization, efficiency, and accelerated design processes intensifies, achieving high-fidelity CFD simulations becomes even more crucial. Through three compelling case studies, this blog will explain how Cadence Fidelity CFD software enhances turbomachinery design for improved performance, making every RPM count.

Entropy distribution in a centrifugal compressor

Case Study I: Toyota Enhances Turbocharger Compressor Efficiency by 1.2%

Toyota Motorsports initiated a project aimed at improving the efficiency of its turbocharger compressor using Cadence Fidelity CFD software. The primary objective of the project was to enhance compressor efficiency while ensuring structural integrity and meeting choke mass flow requirements.

The project encountered several challenges due to the complexity of existing turbocharger components, making traditional physical prototype methods impractical. To address this, the team used numerical optimization, focusing on optimizing compressor impellers near the structural limits of their materials.

A multi-disciplinary approach combining CFD and finite element analysis (FEA) helped in enhancing isentropic efficiency, total pressure ratio, and operating range, all while keeping von Mises stresses within safe limits. The optimization process initially included 154 parameters, which were reduced to 33 critical design variables, supported by a robust meshing strategy utilizing Fidelity Autogrid to maintain mesh quality across design iterations.

Results

The optimization process resulted in notable performance enhancements, as illustrated in the figure below. Two standout designs were identified, achieving all aerodynamic and structural goals. Specifically, design D1 achieved an 8.0% increase in the pressure ratio and a 1.4% rise in efficiency, along with an extended stall margin.

Comparison of original geometry and selected designs (D1 and D2)

This case study demonstrates the effectiveness of multi-disciplinary optimization in enhancing turbocharger compressor efficiency, highlighting the potential of integrated computational methods to improve turbomachinery design in motorsports and automotive engineering.

Case Study II: ENTECHMACH Boosts Centrifugal Compressor Performance with 6.5% Efficiency Gain

ENTECHMACH, a leading power engineering company specializing in advanced compressors and steam turbines, recently launched a modernization project for a three-stage air centrifugal compressor. The project aims to improve performance and reliability by enhancing polytropic efficiency, increasing pressure ratios, and reducing power consumption.

The existing compressor faced several challenges, including reliability issues with axi-radial impellers, stator failures due to inappropriate material selection, and subpar performance metrics characterized by low discharge pressure and high-power consumption. To address these issues, ENTECHMACH utilized Fidelity Fine Turbo Solver and Fidelity Optimization Option for an in-depth flow simulation and optimization process.

Second impeller streamlines

Fidelity Fine Turbo enabled the precise mapping of compressor performance, highlighting key areas for improvement. Design optimization using Fidelity Optimization focused on flow paths under varying conditions, introducing innovations like combined vane diffusers. A 40-million-element mesh model created with Fidelity Autogrid facilitated detailed simulations that confirmed design enhancements.

Results

The redesigned compressor demonstrates significant advancements, featuring an approximate 6.5% increase in polytropic efficiency and achieving a pressure ratio of 4.5. Furthermore, there has been a remarkable improvement in the surge margin, alongside a substantial reduction in power consumption. With these improvements, the compressor exceeds performance expectations, thereby reinforcing ENTECHMACH’s reputation for quality and innovation within the industry.

Case Study III: Fully Coupled Dynamic Engine Simulation of a Gas Turbine

The aerospace industry aims to meet the EU’s Flightpath 2050 environmental goals by improving engine efficiency, particularly through advanced simulation tools in the design phase. Cadence has created a full-engine CFD simulation of the redesigned KJ66 micro gas turbine to assess its aerodynamic performance downstream of the combustion chamber. This simulation focuses on unsteady phenomena, such as hot streak propagation and component interactions, aiming for high accuracy with reduced computational costs.

Traditionally, aero-engine simulations have been performed on a component-by-component basis, which can result in discrepancies with actual performance. Cadence's innovative methodology involves simulating the entire engine, employing two-way coupling without needing prescribed boundary conditions between components. This process enhances both accuracy and efficiency. The simulations included a steady-state Reynolds-Averaged Navier-Stokes (RANS) analysis and a more detailed Non-Linear Harmonic (NLH) simulation, utilizing a comprehensive 3D mesh, advanced turbulence models, and a simplified flamelet model for combustion.

Results

The results from the NLH simulation were particularly promising, as they captured tangential non-uniformities and provided a closer approximation of real-world engine behavior. This comprehensive approach resulted in consistent and efficient flow throughout the engine’s components, helping to achieve a more balanced engine performance.

Illustration of full engine simulation methodologies

The integration of CFD tools, such as Fidelity CFD, into the design workflow of turbomachinery is enhancing design and optimization across various industries. The case studies presented highlight how organizations such as Toyota and ENTECHMACH have successfully leveraged these solutions to enhance efficiency, reduce power consumption, and achieve superior performance metrics. As the complexity of industrial equipment continues to increase, the need for realistic simulations and a multi-disciplinary approach becomes increasingly critical. By making every RPM count, engineers can ensure that they not only meet but exceed the demands of modern engineering challenges, driving progress in motorsports, aerospace, and beyond.

For insights into the theoretical foundation and practical use of turbomachinery CFD simulation, read the eBook 'Engineer’s Guide to Simulating Turbomachinery.'