Prediction on the axial water thrust characteristics of pump turbine runner under partial load

Abstract

Abstract For the high head pump turbine, the unit instability during its operation mainly dues to the hydraulic vibration inside the machinery, which will cause the mechanical fatigue failure under certain circumstances. In this paper, the flow pattern and the runner axial water thrust in turbine model under partial load were analyzed by numerical simulation. The internal flow field instability and vortex load characteristics of the runner were analyzed to obtain the reasons for the different axial water thrust characteristics of the runner under two different loads. The results showed that due to the reduction of the guide vane opening, the flow rate is smaller at 50% load, and the free flow vortex structure on the high-pressure side of the runner blade inlet strengthens the impact of the water flow on the runner. Moreover, when the pressure difference between the runner blades decreases and the axial water thrust of the blades decreases, the total axial water thrust of the runner decreases and fluctuates frequently with time.