A Comparative Study of Varying Incidence Angle Effects on a Low-Reynolds-Number Compressor Cascade Based on Experiments and Low-Fidelity and High-Fidelity Numerical Simulations

Abstract

The trend towards higher bypass ratios and downsized cores in modern compressorsleads to locally reduced Reynolds numbers, intensifying flow separation and unsteadiness,which limits the reliability of RANS models and motivates the use of LES as a feasibleand attractive high-fidelity approach for these conditions. In this paper, we assess thecapabilities of low- and high-fidelity numerical tools for predicting the effects of varyingincidence angles for a linear compressor cascade at a Reynolds number of 150,000 anda Mach number of 0.6 based on the inflow conditions. The comparison is supported byexperiments carried out at the Transonic Cascade Wind Tunnel at the DLR in Cologne,which feature an incidence angle variation of plus/minus 5 degrees. Particular emphasisis put on the numerical setup to reproduce the cascade experiment, discussing the effectsof spanwise domain size, axial-velocity density ratio and inflow turbulence. The effectsof the incidence angle variation are studied on the basis of instantaneous and mean flowquantities with a focus on separation, transition and loss mechanisms.