Abstract: In order to explore the physical mechanism of rotating instability (RI) caused by the unsteadiness of tip leakage flow in a given passage，experimental and numerical investigations were carried out for an axial flow compressor rotor. It is found that RI only appears at operating points in a narrow mass flow rang near the stability limit of the test rotor and RI′s mode order varies over time through analyzing the pressure signals that acquired at the casing wall. Based on the experiment，the five-passage simulations were conducted to observe the unsteady flow field. The numerical results show that the characteristics of the unsteady flow near the rotor tip observed in simulations is similar to the characteristics of RI in experiments. The detailed analyses of the simulated instantaneous flow fields indicate that the unsteady flow in a given passage is the self-induced unsteadiness of tip leakage flow. Its impact on the pressure distribution on the pressure side of the passage leads to the self-induced unsteadiness of tip leakage flow appearing in the neighboring passage. Such interaction propagates circumferentially against the rotor rotating direction，thereby leading to the origin of RI.

Key words: Axial flow compressor；Rotating instability；Unsteady flow；Experimental investigation；Numerical investigation；Secondary leakage flow

摘要： 为了探究固定通道中叶尖泄漏流非定常性引起旋转不稳定性(RI)的物理机理，以轴流压气机转子为研究对象分别进行试验和数值研究。通过对机匣壁动态压力信号的分析获取其叶尖流场的非定常特征，发现RI仅在靠近失速边界的狭窄的流量范围工况出现，RI的模态随时间变化。在此基础，采用五通道的数值模拟方法对该转子的内部流场进行了研究。结果表明，数值模拟流场中出现的静压扰动的变化规律和频率特征与试验测量结果一致，多通道的数值模拟成功地预测出RI产生的过程。进一步的流场分析表明，固定通道中出现了泄漏流自诱导非定常性，其对通道压力面近叶尖区压力分布的影响使得相邻叶片的泄漏流也出现自诱导非定常性，该过程在叶尖环面沿周向传播导致了RI现象的出现。

关键词: 轴流压气机；旋转不稳定性；非定常流动；试验研究；数值模拟；二次泄漏流