Zonal Detached-Eddy Simulation of tip-leakage flow sensitivity for a compressor rotor

Abstract

The dependence of the tip-leakage flow to the tip gap size is investigated on the third rotor of a high-pressure axial compressor. Three tip clearances are simulated with a hybrid RANS/LES approach at the nominal operating point with the objective of resolving better the vortical structures in the tip region. The numerical results are in fair agreement with the experiment in the tip region, for the largest gap. The structures depicted in the simulations indicate stronger vortical structures with the larger gaps and a significant blockage induced by them. The results indicate that a double leakage takes place about midchord for the larger gap, changing completely the dynamics of the leakage flow, likely to be causing a vortex breakdown. This also occurs for the intermediate gap but with a lower intensity and no breakdown. The power spectral density at the trailing edge at the tip finally illustrates the higher energy levels for increasing gap values.