Study on the flow characteristic of pump turbine at partial load

Abstract

Abstract Pump turbine adopts the same runner to realize forward pumping for pumping condition and reverse power generation for turbine condition, which is a widely used power equipment in pumped storage power station. Compared with conventional pump units or turbine units, the pump turbine has a complex internal flow, especially under part load conditions, and the vibration and noise problems of the structure are prominent. In this paper, the internal flow characteristics of the pump turbine at 60% load are studied by numerical simulation. The low-frequency pressure pulsation 3.5fn and 5.5fn that occur under this operating condition are analyzed. The results show that under partial load conditions, the opening of the guide vane decreases, the angle of attack of the water entering the runner increases, and the rotating stall phenomenon occurs in the pump turbine. The stall vortices show periodic variations on the blade inlet pressure surface and undergo the processes of vortex reduction, fusion, splitting and increase, respectively. The frequency of change is 0.5 times the runner rotation frequency (0.5fn ). The frequency of the corresponding monitoring points in the 7 blade rotor is 7 times (1fn -0.5fn ), which is 3.5fn .