Abstract: The research progress on rotating stall in axial compressors over last several decades is retrospected. As the key factor of influencing rotating stall in axial compressors， tip leakage flow is selected as the view angle by the authors’ research group to clarify the stall mechanism in axial compressors. The existence of the unsteady tip leakage flow was proved by both the experiment and numerical simulation that the tip leakage flow oscillates at the near-stall points in low-speed and high-speed axial compressors. The unsteady characteristics such as fluctuating amplitude and frequency as well as the three-dimensional flow structure of tip leakage flows in the throttling process up to stall point are closely revealed. It is mainly manifested as two aspects: (1) the tip leakage flow becomes unsteady， and the unsteadiness is enhanced at near-stall point.(2) The interface between tip leakage flow and incoming main flow moves forward during the throttling process， and spills over the rotor leading edge just before the spike stall inception occurs. The driving force of these two flow features is the enhanced impediment of the tip leakage flow against the main incoming flow， which can be measured by the axial momentum balance within the tip range. At last， examples of active/passive stability enhancement techniques using these results are provided. It highlights the potential value in terms of stability control in the actual application.

Key words: Tip leakage flow；Unsteady；Interface；Rotating stall；Flow instability mechanism；Axial compressor

摘要： 首先回顾了近几十年来国际上在轴流压气机内部流动失稳机理方面具有代表性的研究成果，然后介绍了作者研究团队从叶顶泄漏流的视角研究压气机失稳机理所开展的主要工作，研究结果证实了叶顶泄漏流非定常性在低速亚声和高速跨声压气机转子中存在的普遍性，揭示了在节流直至失速工况过程中叶顶泄漏流的非定常波动和三维空间结构特征。主要表现为:(1)叶顶泄漏流由定常变为非定常波动，且非定常波动强度不断增强。(2)泄漏流与主流交界面的轴向位置不断向叶片前缘移动，最终溢出叶片通道，并诱发突尖失速先兆。这两方面特征的内在驱动力是节流过程中不断提高的泄漏流与主流轴向动量比。这些研究成果在发展主/被动扩稳技术和阐释扩稳机理研究中凸显出重要的应用价值。

关键词: 叶顶泄漏流；非定常；交界面；旋转失速；流动失稳机理；轴流压气机