Experimental study of blade tip injection effects on the stability of a axial-compressor was carried out. The rotating stall signal was verified and spike type stall inception was detected when there was no injection

and it was found that the type of the stall inception signal did not change after tip injection was used. The effects of the number of tip injectors

circumferential distribution of injectors and yaw angle of injector on the effectiveness of stability enhancement were measured and analyzed. From the experimental results

it can be concluded that the stability was enhanced by either decreasing the number of injectors while keeping the total mass flow of injectors constant

or by increasing the number of injectors under the condition that the mass flow of a single injector keeps constant

and the stability was decreased by increasing the unevenness of injectors. It was also found that effectiveness of stability enhancement by tip injection was related to the parameters of injection flow in the relative frame of rotor. The association relation between the momentum component of the injection flow along the flow direction of zero incidence angle in the relative coordinate

which is scaled by the momentum of main flow

and effectiveness of stability enhancement was built.