不同转速下跨声速轴流压气机内部流动失稳的机理

以跨声速轴流压气机转子NASA Rotor 67为研究对象,采用数值模拟方法,开展100%、80%及60%转速下跨声速轴流压气机内部流动失稳触发机制的机理研究。数值结果与实验数据的对比分析表明:在3个转速下,数值总性能曲线的变化趋势与实验数据符合一致。通过压气机内部流场的详细分析,得出其基本流动机理。在3个转速下,随着压气机节流,叶顶泄漏涡(TLV)的起始位置逐渐向叶片前缘移动,叶顶泄漏涡也逐渐向相邻叶片压力面偏转,相比近峰值效率点,近失速点时在100%、80%以及60%转速下叶顶泄漏涡的偏转角度分别为3°、6°和9°。在100%和80%转速下,叶顶泄漏涡与激波相互作用所导致的堵塞是触发压气机内部流动失稳的机制,并且在80%转速下,叶顶泄漏涡发生破碎；而在60%转速下,泄漏涡在相邻叶片出现的叶顶前缘溢流(LESF)是触发压气机内部流动失稳的主要机制,叶片吸力面尾缘出现的小尺度附面层气流分离(BLFS)不是主要机制。 

Mechanism of internal flow instability in transonic axial flow compressor at different rotating speeds

A transonic axial flow compressor rotor, the NASA Rotor 67, was chosen to investigate the triggering mechanism of internal flow instability in transonic axial flow compressor at the 100%, 80% and 60% rotating speeds with the help of numerical method. The comparative analysis of numerical results and experimental data showed that the trends of experimental performance curves were finely repeated by numerical results under three design rotating speeds. The fundamental flow mechanism was obtained by the detailed analysis of internal flow field in compressor. As the mass flow rate of compressor reduced at three rotating speeds, the starting position of tip leakage vortex (TLV) moved to the blade leading edge gradually, and tip leakage vortex also turned towards the pressure surface of adjacent blade. The deviated degrees between tip leakage vortex trajectory and compressor rotating shaft for near stall point were 3 degree, 6 degree and 9 degree than that for near peak efficiency point at the 100%, 80% and 60% rotating speeds, respectively. The blockage resulted from the interaction between tip leakage vortex and shock wave led to the internal flow instability in compressor at the 100% and 80% rotating speeds, and tip leakage vortex broken occurred at the 80% rotating speed. While at the 60% rotating speed, the leading edge spilled flow(LESF) of blade tip caused by tip leakage vortex near adjacent blade was the primary cause of internal flow instability in compressor, while a small scope boundary layer flow separation(BLFS) near the trailing edge of blade suction surface was not the primary cause.