A 45° circumferential inlet pressure distortion screen was designed and the effects of screen-induced circumferential inlet pressure distortion on axial flow compressor stage were investigated at a high speed subsonic compressor test rig. The performance characteristics for the rotor with circumferential inlet pressure distortion and clean inlet flow were compared at middle-speed.The circumferential pressure distributions at three axial locations(rotor inlet

rotor outlet and stator outlet) were measured.The results show that the inlet flow distortion has weak effects on the compressor stage at middle-speed.In addition

the enlarging and moving of the distortion-section are not obvious at rotor outlet

but it is enlarged about 100 percent at stator outlet;the distortion is enhanced at rotor outlet and decayed at stator outlet.However

with inlet distortion the pressure ratio of this compressor rotor is improved 1.8 percent and the equivalent mass flow reduced 2.5 percent at near-stall condition in comparing with clean inlet flow.