Effects of Radial Loading Distribution on Partial Surge Initiated Instability in a Transonic Axial Flow Compressor

Abstract

Partial surge is a new type of instability inception in transonic axial flow compressors and occurs in the form of axisymmetric low-frequency disturbances localized in the hub region. In this study, the evolution of instability in a transonic axial flow compressor at different rotor speeds shows that at 65% of the design rotor speed, partial surge does not occur; at 78% of the design rotor speed and higher, partial surge occurs and leads to compressor instability. The result of RANS simulation of the same compressor then suggests that the level of blade loading in the hub region could be highly correlated to the occurrence of partial surge. Next, the radial distribution of blade loading near the stall point is varied by introducing inlet distortion — alternately mounting specially designed screens at the inlet of the compressor. The experimental results suggest that high hub loading near the stall point would lead to partial surge initiated instability. The general effects of radial loading distribution on the type of stall inceptions are also discussed.