水泵水轮机泵工况下近设计点驼峰现象的流动机理研究*

中高比转速水泵水轮机泵工况下近设计点驼峰严重制约了其稳定运行范围，是制约抽水蓄能电站安全与经济运行的关键问题之一。作为流动问题的宏观表现，驼峰现象必然与水泵水轮机内部的非定常流动存在密切关系。为此，基于试验和数值模拟，对水泵水轮机泵工况下可调导叶流道内的非定常流动进行研究，探究模型机泵工况下的压力脉动特性、非定流动机理及与性能曲线稳定性之间的关系。结果表明：在设计和小于设计工况下，可调导叶流道内均存在两种显著的周期性压力脉动。模型机泵工况下的流量扬程曲线在0.45~0.75倍设计流量区间内出现驼峰，频域分析清晰地揭示了以上两种压力脉动是对该驼峰存在重要影响的流动参量。

Study of Hump Instability Phenomena in Pump Turbine at Large Partial Flow Conditions on Pump Mode

For middle-and high-specific speed pump turbines,the hump instability appearing at large partial flow conditions seriously restricts its stable operation range.These phenomena relate closely to the inner unsteady flow in pump turbine.We investigate the characterization of pressure fluctuation and the mechanism of unsteady flow by an experimental and numerical studyof the unsteady flow occurring among the adjustable blades.For pump working at either full or part load conditions,two kinds of periodic pressure pulsations in the diffuser vane have been observed and analyzed.A hump instability appears only when the actual flow rate of head curve is 0.45-0.75 times of the designed value,and our frequency analysis further shows that its appearance is closely related to the two above pressure fluctuations.