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

以NASA Rotor 67为研究对象，采用非定常数值模拟方法，开展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改善的研究，并且揭示缝轴向偏转角的变化对其扩稳能力和扩稳机理的影响。结果表明，不同轴向偏转角的缝均提高了压气机的稳定裕度，但是均降低了压气机的峰值效率。反叶片角向缝获得的稳定裕度改进量和峰值效率改进量分别约为24.22%和-1.19%。随着缝的轴向偏转角由负向正变化，缝的扩稳能力逐渐减弱，缝带来的峰值效率损失亦逐渐减少。流场分析表明，实壁机匣时，压气机的失速类型为叶顶堵塞形式的突尖型失速。通过感受叶片通道和叶顶吸/压力面的压差，反叶片角向缝对泄漏流进行抽吸和射流作用，一方面消除了泄漏流及其泄漏涡扩散带来的负面影响，另一方面激励了泄漏流，提高了泄漏流的速度，降低了泄漏流的总压损失，增强了叶片的做功能力。随着缝的轴向偏转角由负向正变化，由于缝能够利用的叶顶载荷从两个减成一个，缝的抽吸和射流作用均减弱，泄漏流的速度降低，泄漏流的总压损失提高，叶片的做功能力减弱，这就导致缝的扩稳能力减弱。

Effect of slot casing treatment and it's axial deflection angle on stability of transonic axial flow compressor

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.