STALL INCEPTION AND DEVELOPMENT IN AN AXIAL-FLOW AEROENGINE

This paper describes the phenomenon of stall and surge in an axial flo w aeroengine using fa.st response static pressure measurements from th e compressor of a Rolls-Royce VIPER engine. It details the growth of f low instability at various speeds, from a small zone of stalled fluid involving only a few blades into the violent surge motion of the entir e machine. Various observations from earlier theoretical and compresso r rig results are confirmed by these new engine measurements. The main findings are as follows: (1) The point of stall inception moves rearw ard as engine speed increases, and is shown to be simply related to th e axial matching of the compressor. (2) The final unstable operation o f the machine can be divided into rotating stall at low speed and surg e or multiple surge at high speed. (3) The inception process is indepe ndent of whether the final unstable operation is rotating stall or mul tiple surge. (4) Stall/surge always starts as a circumferentially smal l flow disturbance, rotating around the annulus at some fraction of ro tor speed.