KY EPSCoR: Axial Compressor Flow Behavior Near The Aerodynamic Stability Limit

The operating range of an axial flow compressor is limited by rotating stall and surge. Either or both of these flow instabilities may occur at the compressor stall line. In surge the compressor experiences large amplitude fluctuations in the total annulus averaged flow at a relatively low frequency. When rotating stall is encountered one or more cells are found to rotate around the circumference in the same direction as rotor blade rotation, but at a fraction of the rotational speed. The stall cell may extend over part or the entire span of the annulus. These flow phenomena not only degrade the performance of the compression system, but can also impact structural durability. Hence, axial compressors have a safety margin between the compressor operating line and the stall line. The proposed research experimentally investigates the rotating stall inception process in axial flow compressors.