Experimental and numerical investigations were conducted to study the effects of axial positions of circumferential grooved casing treatment on compressor performance.Experiments of three different axial positions of circumferential grooved casing treatment were performed in a subsonic rotor.The experimental results show that three axial positions of groove casing treatment extend the steady operating range of the compressor at two rotating speeds.Groove with unchanged axial position has the best effect in extending the steady operating range

followed by the backward axial position moving.The calculated overall tendency for stall margin improvement fitted well with the experiment.The fundamental flow mechanism was obtained by in-depth analysis of the flow-filed at the blade tip

based on the effect of circumferential grooved casing position on the compressor performance.