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

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