Effect of Tip Injection on Tip Leakage Flow Structure in Axial Compressor

Tip Leakage flow of the compressor blade is one of the effective factors in performance of axial compressors, which can also damage the compressor blades. In this paper, the effect of air jet injection to reduce the destructive effects of tip leakage flow on the performance of the axial compressor is investigated. For this purpose, the numerical analysis of the flow in the NASA rotor 37 axial compressor is performed using CFX software. Initially, the compressor performance curve in the without injection mode was compared with the experimental results and a good agreement was observed. Then, considering the injection of air for one passage the performance curves of the compressor in comparison with the non-injection mode were examined. By injecting air, the pressure ratio increases and the adiabatic efficiency of the compressor decreases at the same mass flow rates. It was found that air injection reduces the drops in the axial compressor and weakens the created vortices. This reduces the rotor drop coefficient and also reduces the angle of attack. Accordingly, injection increases the stall margin and increases the operating range of the compressor by 6% and 66%, respectively. Also, the tip leakage flow has less power than in the without injection condition, which results in less drop.