Analysis of Stable Rotating Stall in a High Speed Axial Compressor

Abstract

Experimental studies of transonic rotating stall phenomena have used measurements of unsteady casing pressure to infer spatial and temporal scales associated with part-annulus stall cells. These scales are often described with characteristics such as cell counts and rotating speeds derived from either visual inspection of pressure signals or a discrete Fourier series of the circumferential distribution of pressure. The present work utilized experimental measurements from a new, modern, transonic compressor experiment in order to investigate the physics of post-stall transients in a compressor with a low hub-tip ratio. The results of this paper will show that the stall cells were highly random in nature, with spatial correlations that were less than a full revolution and temporal convergence times of greater than ten revolutions. This limited the utility of the Fourier analysis in understanding the spatial structure. The data reduction methods provide a framework for characterizing the flow physics and compression system dynamics of post-stall compressor performance.