Prediction of the characteristic pressure pulsations in a reversible pump-turbine

Abstract

Reversible Pump- Turbine turbomachines are frequently used in peaking load hydroelectrical power plants. These plants contribute to satisfy the energy demand during peak load periods. Its dynamic behaviour is influenced by the flow structures developed along the distributor and runner vanes. This behaviour depends both on the internal design of the machine and its operating conditions, whether it works as pump or as a turbine. High-amplitude pressure pulsations appear due to the rotor-stator interaction phenomenon, and under certain operating conditions, the frequency of these pulses can seriously affect the structural integrity of the machine. The goal of this study is to assess the dynamic behaviour of a low-specific-speed reversible pump-turbine when working both as a turbine or as a pump. For validation, the obtained numerical results for the pressure pulsation in both operating modes are compared to experimental results measured on a working prototype. These results could be useful to enhance the knowledge concerning the behaviour of the pressure pulsations due to the internal flow dynamics into the machine.