Thermal Endwall Effects on Spanwise Mixing in a High-Speed, Multi-Stage Axial Compressor

Authors

Nicholas J. Kormanik III - Purdue University, United States of America
Joseph C. Brown - Purdue University, United States of America
Douglas R. Matthews - Purdue University, United States of America
Nicole L. Key - Purdue University, United States of America

Abstract

The turbomachines found in today’s land and air-based gas-turbine engines feature many aerodynamic challenges that were not as evident in past designs. As designers have pushed the limits of how much energy they can get out of the engine, lower aspect ratios, higher relative tip clearances, and higher loading across multiple stages have resulted in enhanced spanwise mixing through turbulent diffusion and secondary flows. With industry relying heavily on computational tools to predict the performance of these modern turbomachines, designers are susceptible to underpredicting spanwise mixing effects if they do not apply the proper calibrations and adjustments to their models. While traditional design tools typically include steady RANS simulations which incorporate mixing planes that average out flow properties in the streamwise direction, it can also lead to these properties becoming transported inaccurately in the spanwise direction. This can even result in mismatched stages and incorrect 1D predictions in performance metrics. One example that has been shown in previous studies involves properly accounting for the lost information observed from circumferential averaging of the vorticity transport across mixing planes. By taking this into account, steady RANS simulations can be adapted to better reflect the proper spanwise mixing. This is useful as it keeps companies from having to perform costly and time intensive unsteady and LES computational methods. To achieve this spanwise mixing correction, this paper will seek to apply the enhanced turbulent diffusion method used in previous studies by increasing eddy viscosity in a steady RANS model using ANSYS CFX. Through this method, it will attempt to reconcile differences between experimental and steady, computational data and extend the research by applying it to a modern-day, high-speed, axial compressor. It will also explore computationally how temperature effects at the end walls can be influenced by this change/enhancement in spanwise mixing and offer insight into how this knowledge can be applied to experimental test cases.