An Experimental Study of the Inception of Rotating Stall in a Single-Stage Low-Speed Axial Compressor

There are two established mechanisms, spike and modal inception, by which rotating stall is initiated in an axial flow compressor. Whilst the “Critical incidence hypothesis” and the “Zero slope criterion” are useful ideas in explaining the different stability boundaries for spikes and modes they do not provide the designer with a predictive tool. A detailed experimental investigation utilising a single-stage low-speed compressor is presented in which the aerodynamic environment of a rotor blade row is changed (rotor geometry is held fixed) so that it exhibited both spike and modal inception upon throttling into stall. The dominant mechanism of stall inception was found to be dependent on both the inlet flowfield and the downstream stator. The measurements are analysed and show that the meridional acceleration across the tip region of the rotor influences the mechanism by which rotating stall is incepted. This research is presented as a contribution towards the prediction of the stall inception mechanism.Copyright © 2007 by ASME