Numerical study of rotor tip ejecting

The stall margin of compressor can be effectively improved by rotor tip injection, but the available injectors are complex in structure and will increase the engine weight. The purpose of this paper is to explore a new type of injection, which is easy to implement in compressors without increasing the total weight. A casing modification (CM) method was used on the casing near the rotor tip leading edge, so that the axial velocity near rotor tip leading edge improved, which has a similar effect on the rotor tip injection. The method was numerically tested on the rotor 37, and it was concluded that, the CM method could improve the rotor stall margin by 6.7%, and the efficiency and pressure ratio are improved slightly. Comparison of different schemes of CM method shows that, the location of CM influences stall margin most obviously. The analysis of rotor tip flow field indicates that, the CM method could increase the rotor tip axial velocity, push the tip leakage vortex downstream, weaken the blockage at the rotor tip region, and enhance stability of the rotor therefore.