Experimental investigation on aerodynamic instability of axial flow engine

Experiments were performed to investigate the aerodynamic instability of axial flow aeroengine during throttling operation. The aerodynamic destabilization route and mechanism were revealed through qualitative analysis and data processing. It was observed that the variation of form and intensity of pulsating components of stator casing wall static pressure signal of the first compressor stage was closely related to the degree of end wall flow separation of upstream rotor. Further data analysis manifested that the variation of compressor stator casing wall static pressure fluctuations could be represented by probability density analysis. A new method of identifying the stall precursors by means of sensing the degree of flow separation in the first compressor stage, rather than to detect modal and/or spiky disturbances inducing compressor rotating stall directly, is suggested, which is believed to be promising because the flow separation in the first compressor stage occurs far early before the occurrence of spikes or modes in the compressor stages with high loadings and high hub-to-tip ratios.