Short Length-Scale Rotating Stall Inception in a Transonic Axial Compressor: Experimental Investigation

To improve the understanding of spike-type stall inception of a transonic axial compressor, measurements of the unsteady static pressure in the rotor endwall region are analyzed. At design speed, a detailed experimental investigation of the unsteadiness of the pressure field at the rotor endwall at near stall condition shows a strong fluctuation of the tip clearance flow. Both vortex strength and -trajectory oscillate randomly. Analysis of the wall pressure time histories during stall inception suggests that spike-type disturbances of the flow field correlate with an upstream motion of one blade passages shock front. In addition, the evolution of a stall cell could be visualized by means of static wall-pressure contour plots.