缝式机匣处理及其轴向偏转角对跨声速轴流压气机稳定性的改善

The unsteady numerical simulation method is utilized to carry out the investigation on slot casting treatment and the effect of its axial deflection angle on the stability of the transonic axial flow compressor-NASA Rotor 67. The effect of the variation of axial deflection angle on the ability and mechanism of expanding stability for slots is revealed. The results show that all the slots with different axial deflection angles can improve the compressor stability margin, but reduce the compressor peak efficiency. The improvements of stability margin and peak efficiency generated by the reversed blade angle slot are about 24.22% and -1.19%, respectively. As the axial deflection angle of the slot is changed from negative to positive, the ability of expanding stability of the slot is weakened gradually, and the loss of peak efficiency caused by the slot is reduced gradually. An analysis of the flow field shows that the stall of the compressor is spike stall in the form of the blade tip blockage when the casing is solid wall. By feeling the pressure difference between the upstream and downstream of the blade passage and the pressure difference between the suction and pressure surface of the blade tip, the slot with the reversed blade angle can suck and inject the leakage flow. Therefore, the negative effects of the leakage flow diffusing and the corresponding vortex are eliminated; the leakage flow is also excited, and it leads to the improvement of the leakage flow velocity, the decrease of the total pressure loss of the leakage flow and the enhancement of the work ability for the blade. When the axial deflection angle of the slot is changed from negative to positive, the blade tip load, which can be use by the slot, is reduced from two to one. So, the suction and injection ability of the slots are weakened, and the velocity of leakage flow is lowered. Consequently, the total pressure loss of leakage flow is improved, and the work ability of blade is weakened. As a result, the expanding stability of the slot is weakened.