Investigation on mechanism of perfomance improvement for compressor with new type of casing treatment with inlet distortion

Influences of the performance and flow-field of subsonic axial-flow compressor are investigated with full-annulus unsteady numerical method with self recirculation casing treatment under inlet distortion to uncover the flow mechanism. Inlet distortion is made by setting barriers in the inlet radial passage. The numerical calculative results show that besides gaining 6.8% stall margin improvements, the performance of compressor can be improved with self recirculation casing treatment under inlet distortion and the effect of increasing efficiency is better than the effect of increasing total ratio. The fundamental flow mechanism is obtained by analyzing the flow-filed in rotor passage in details. The detailed analysis of the flow-filed in compressor indicates that the separated locations of blades suction boundary in some tip passage move toward blade trailing with casing treatment and the highest value is about 11% the tip chord length, weakening the bad effect of flow separation and preventing leakage flow spill to adjacent tip passage. When injecting setups face the blade tip passage, the effect of restraining tip clearance leakage flow is the best.