Experimental investigation of flow characteristic of tip leakage flow in an axial flow compressor rotor

Abstract

Tip leakage flow fields in a small-scale high-speed subsonic axial flow compressor rotor were investigated by virtue of the steady and casing instantaneous pressure measurements over wide stable operating range. Fast Fourier transformation and short time Fourier transformation analyses were conducted to elucidate the flow characteristics at different operating conditions, with an emphasis on extending experimental database to validate the previous and subsequent numerical investigations, which would be crucial to the understanding of the origin of tip flow unsteadiness. The measured quasi-steady flow characteristics agreed well with the flow features of tip leakage flow from previous steady simulations. The unsteady flow characteristic of tip leakage flow was the appearance of rotating instability, which was of varying frequency closely related to tip loading variation. An agreement between the unsteady flow characteristics of tip leakage flow from the current measurements and from the previous unsteady simulations to some extent indicated that further systematical unsteady simulations and a deeper quantitative validation of simulation results should be made so that the origin of rotating instability could be uncovered precisely.