Experimental investigations of dominant unsteady surface pressure in the corner separation region of a high-subsonic compressor cascade

The wall pressure fluctuations on compressor blades, referred to as unsteady surface pressure (USP), significantly impact vibration, noise, and aerodynamic performance. A comprehensive understanding of USP in the corner separation region can provide guidance for performance improvement of a compressor based on the mechanism analysis. However, due to the high Reynolds number of the flow, narrow space, thin blade walls, and large geometric deflection angles, obtaining the USP with a corner separation phenomenon in a high-subsonic compressor either experimentally or by numerical simulations is challenging. The aim of this work is to experimentally investigate the dynamic characteristics of the unsteady surface pressure in a high-subsonic compressor cascade suffering from a large-scale corner separation. The USP of the point-matrix on the measured surface is measured using the non-embedded measurement (NEM) method. The frequency features and dominant fluctuation areas on the blade suction and end wall surfaces within the Strouhal numbers range from 0.326 to 2.285, corresponding to the frequency range of 1-7 kHz, which are captured for the first time. The results show that three main frequency bands are present under both stable ( M a = 0.6 i = 5.0 ° ) and unstable conditions ( M a = 0.6 i = 7.5 ° ). It is found that the high-fluctuation regions of the three frequency bands occupy different spatial positions. Furthermore, combining the experimental results near the wall with the high-fidelity detached eddy simulation results far away from the wall, the physical phenomena related to the different frequency bands are explored through the spatial characteristics of the main fluctuation areas.