Time-frequency analysis of the axial flow compressor end wall flow at near stall conditions

To identify the flow pattern of a single-spool turbojet axial flow compressor at near stall conditions, the compressor end wall static pressure signals were analyzed using time-frequency analysis technology. The results show that at near stall conditions, the endwall flow of the first compressor stator varies dramatically compared to other stators. As the operating point runs close to the surge line along the operating line, a broad band signal centered on 550 Hz occurs and gradually builds up. The observed end wall flow patterns can be used to assess the stall margins during engine throttling, and thus, it has certain value in engineering application.