Numerical Study on the Flow and Structural Characteristics of a Large High Head Prototype Pump-Turbine under Different Operating Conditions

During the operation of pumped storage power stations, complex operating conditions can lead to different internal flow characteristics, which can cause different vibration characteristics or even damage to the structural components of the pump-turbine units. The time–frequency characteristics of the structural components’ response are of great significance for the safe operation of the unit. In this study, a three-dimensional flow field and structural field model of a large high head prototype pump-turbine is built in order to study the flow and the flow-induced dynamic response characteristics in different turbine operating conditions. The analyzed results show that the maximum deformation occurs at the inner head cover, and the maximum value of stress is located at the fillets on the outlet side of the stay vanes. Under the 50% load condition, the vortices in the runner caused by changes in the opening of the guide vanes result in the main response frequency of 4 fn of the stationary components. The research results can provide references for the structural optimization design of other pump-turbine units.