Dynamic Characteristic Analysis of a Pump-Turbine Unit under the High Pressure Pulsation Operating Condition - Fluid Dynamics Analysis

The pumped storage power plants play an irreplaceable role in optimizing the energy structure of various countries, promoting the development and utilization of new energy sources, and protecting the ecological environment. The water heads of the pumped storage power plants are very high and generate high pressure pulsations on the pump-turbine units. The pressure pulsation of rotor-stator interaction is one of the major pressure excitations, which can induce high stress on the rotating structures and stationary structures of the pump-turbine units. This paper investigates the dynamic characteristic of unsteady flow of the high-head reversible pump-turbine unit under a high pressure pulsation operating condition by means of computational fluid dynamics (CFD) simulations, and analyses the characteristics of pressure pulsation caused by rotor-stator interaction (RSI) in the time domain and the frequency domain. The results reveal that high pressure pulsations in the pump-turbine flow channels are related to the rotational frequency, the number of runner blades, and the number of guide vanes. The design improvement suggestions are proposed to reduce the pressure pulsation of the turbine unit and provide references for other pump-turbines. The calculated pressure files can be used to perform flow-induced dynamic stresses in both rotating and stationary structures of the pump-turbine unit.