对转压气机叶顶间隙涡非定常数值研究

Study of Transient Tip Leakage Vortex Characteristics in a Contra-Rotating Compressor

以双排对转压气机为研究对象,研究了叶顶间隙对对转压气机性能参数的影响规律。针对大叶顶间隙时对转压气机性能严重恶化问题,从非定常的视角刻画了大叶顶间隙下,工作点变化对其内部流动特征的影响规律,结果表明:随着流量减小,对转压气机中上、下游转子叶尖泄漏涡非定常波动均有增强趋势,下游转子首发失速是对转压气机流动失稳的主要诱因。小流量工况下,叶顶主间隙泄漏涡与次泄漏涡的非定常干涉是下游转子内部非定常波动的主要成因;该工况时,下游转子叶顶间隙涡非定常周向波动强度强于径向波动强度,其影响范围也主要表现在叶顶前缘50%弦长范围内。频谱分析显示,上游转子叶尖泄漏涡非定常波动频率略小于下游转子区,下游转子区静压波动幅值约为上游转子的5倍。

An axial contra-rotating compressor（ACRC） has been studied by numerical simulation to investigate the effects of the tip clearance sizes（TCS） on the performance of ACRC.The detailed flow characteristics of the compressor at different operating points with larger TCS have been analyzed via transient numerical simulation method to explain the phenomenon that the performance of the ACRC tends to deteriorate seriously with the increasing of the TCS.The conclusions are as follows：The unsteady fluctuations of the tip clearance leakage vortex both in the upstream and downstream rotors enhance as the mass flow rate reduces gradually.Besides,the downstream rotor enters the state of stall earlier and induces the stall of the whole compressor.When the compressor works at the operating point with smaller mass flow rate,the interaction between the main tip clearance leakage vortex and the secondary leakage vortex causes the transient fluctuation of the downstream rotor.Moreover,the unsteady fluctuant intensity of the downstream rotor along the circumferential direction is stronger than that along the radius direction,and the involved area of the leakage flow is mainly in front of 50%blade tip chord.The frequency spectrum analysis of the unsteady static pressure shows that the fluctuation frequencies of the tip clearance leakage flow in the upstream rotor is slightly smaller than that of the downstream rotor.However,the maximum static pressure amplitude of the downstream rotor is about 5 times as large as that of the upstream rotor.