Pressure pulsation analysis of runner and draft tube of pump turbine under different working conditions

As the core component of pumped storage power station, the pump turbine usually needs to adjust the operating condition point according to the electricity demand during operation. Pressure pulsation is an inevitable phenomenon in the operation of pump turbine, which affects the safe and stable operation of the unit. In this paper, the method of combining numerical simulation and experiment is adopted to carry out three-dimensional full flow channel numerical simulation of the pump turbine by using CFD. The flow pattern and pressure pulsation of the runner and draft tube of the pump turbine were analyzed at the three working conditions of PL (50% maximum load), BEP (70% maximum load) and HL (90% maximum load). It is found that under the three conditions, the pressure pulsation from the leafless area to the downstream of the draft tube shows a weakening trend. Because the flow pattern in the bladed area of the unit is poor, the pressure pulsation in the bladed area is the most obvious. From low load to high load, the pressure pulsation tends to weaken at first and then increase. Combined with flow pattern analysis and vortex analysis, it can be concluded that the number and scale of vortex flow are positively correlated with the pressure pulsation, and the vortex flow inside the unit is an important factor that causes the flow disorder inside the unit, and then becomes an important factor that affects the pressure pulsation inside the pump turbine unit.