随着可逆式水泵水轮机向高扬程、高比转速和大容量发展，含气率及水可压缩性对其内部流动的影响更加显著，导致其运行稳定性问题更加突出，成为制约抽水蓄能电站安全与经济运行的一个关键难题。旋转失速是可逆式水泵水轮机内部一种发展充分的旋转不稳定流动现象。研究表明，含气率、水可压缩性与旋转不稳定流动之间存在重要的关联，是当前尚未解决的技术瓶颈与科学问题。本项目应用试验及数值仿真，研究不同含气率对水可压缩性的影响，结合压力脉动与PIV测量，探究旋转不稳定流动结构；在此基础上，建立适用的气液混合弱可压缩计算模型；构建空间流动结构解析模型，探究旋转不稳定流动的发展规律，找到引起旋转失速的先兆流动结构，并提出通过抑制先兆流动来改善旋转失速的控制策略。期望通过该研究，促进水力机械内旋转不稳定流动的物理认识，同时为高扬程大容量水泵水轮机安全稳定运行提供理论指导。

With the development of high head, high specific speed and large capacity of the reversible pump turbine, the influence of gas fraction and compressibility of water on the internal flow becomes to be significant, resulting in more prominent operational stability problems, which has become a key problem that restricts the safety and economic operation of pumped storage power stations. Rotating stall is a well-developed rotating unstable flow phenomenon inside a reversible pump turbine. Studies have shown that there is an important correlation between gas fraction, water compressibility and rotating unstable flow structures, which is one of the technical bottlenecks that has not yet been solved. This project applies experiments and numerical simulations to study the effects of different gas fraction on water compressibility, and combines pressure pulsation and PIV measurement to explore the rotating unstable flow structures; on this basis of experimental measurements, a suitable gas-liquid hybrid weak compressible calculation model will be established; to construct an analytical model of spatial flow structure, this research explores the development of rotating unstable flow, find the precursor flow structure that causes the rotating stall, and proposes a control strategy to improve the rotating stall by suppressing the flow precursor. It is expected that through this research, the physical understanding of the unstable flow in the hydro-mechanical machine will be promoted, and a theoretical guidance for the safe and stable operation of the high-head large-capacity pump turbine will be provided.