Hump characteristic is one of unique hydraulic instabilities of pump-turbines, which restricts the stable and safe operating range of the units. High-amplitude pressure fluctuations could be observed in the hump region, leading to hydraulic vibration of pumped storage power plants. To reduce the high-amplitude pressure fluctuation in the hump region, two optimization strategies for high-pressure edge shape of runner blades have been proposed. One is to increase the outlet angle near the shroud and the other increases the radius near the shroud. A large eddy simulation, which has been validated using performance and pressure fluctuation experiments, was performed to study the optimization effect. The valley point (0.65Q_BEP) in the hump region was selected for conducting time and frequency analyses under different optimization strategies. Analyses show that the pressure fluctuations were primarily caused by the rotation of three low-pressure regions at the circumference of the guide vanes. Both optimization strategies reduced the stall vortices formed in the three low-pressure regions and mitigated the rotating stall phenomenon. The influence of the runner-outlet geometries on pressure fluctuations is primarily reflected in the amplitude reduction of the dominant low frequency 0.2f_n (where f_n denotes the rotational speed) in the vaneless region and guide/stay vanes. Compared with strategies involving larger outlet angles near the shroud, this strategy of increasing the radius can more effectively reduce the amplitude of the dominant low frequency, and it makes the circumferential distribution of pressure fluctuations more uniform. These findings can help guide efforts in pump-turbine design optimization, which have been applied in a 700 m head pump-turbine design.

驼峰特性是水泵水轮机特有的水力不稳定性之一，限制了机组的稳定安全运行范围。在驼峰区可以观察到高幅度的压力波动，导致抽水蓄能电站的水力振动。为了减少驼峰区的高振幅压力波动，提出了两种转轮叶片高压边缘形状的优化策略。一种是增大护罩附近的出口角度，另一种是增大护罩附近的半径。使用性能和压力波动实验验证了大涡模拟，以研究优化效果。谷点 (0.65 Q _BEP) 在驼峰区域被选择进行不同优化策略下的时间和频率分析。分析表明，压力波动主要是由导叶圆周上三个低压区的旋转引起的。两种优化策略都减少了三个低压区形成的失速涡，减轻了旋转失速现象。流道出口几何形状对压力波动的影响主要体现在主要低频 0.2 f _n的振幅降低（其中f _n表示转速）在无叶片区域和导向/保持叶片。与在护罩附近涉及更大出口角度的策略相比，这种增加半径的策略可以更有效地降低主导低频的幅度，并使压力波动的周向分布更加均匀。这些发现有助于指导泵涡轮设计优化工作，这些优化已应用于 700 m 扬程泵涡轮设计。