Flow field structure in the rotor blade passage of a low speed axial flow compressor both under uniform inlet flow and distorted flow simulated by adding baffles with 50% blocking ratio was investigated using PIV(Particle Image Velocimetry) technique.Experimental results indicate that there are four different flow field structure types in the compressor rotor passage at different circumferential positions under inlet distortion.Inlet distortion makes the intensity of vortex disturbance

velocity decrement and separation in the rotor passage rise greatly.This will affect the performance of compressor heavily.The experiment also testifies the limitation of the classical parallel compressor theory.