Vortex structure and pressure fluctuation of a pump-turbine in pump mode using large Eddy simulation

Pump-turbines are usually used to ensure the stability of power system frequency and make up for the shortcomings of the intermittent nature of new energy such as wind energy. They are an important part of modern power systems. The Large Eddy Simulation (LES) method is used to study the vortex characteristics and pressure fluctuation intensity of the model pump-turbine working in pump mode. Results show that the wake vortex of the impeller has a great influence on the internal flow field of the pump-turbine, which is developed from the vortex structure near the suction surface of the blade. The distribution of trailing edge shedding vortex of guide vanes and shock vortex around tongue is closely related to the wake vortex of impeller. The wake vortex is divided into alpha and beta according to the distribution range along the blade height. Their motion law and dissipation rate are different, and the influence of the alpha vortex on the flow field is greater. The distribution of pressure fluctuation intensity near the wall corresponds to the vortex structure, which indicated that the vortex is an important factor in pressure fluctuation. It is of great significance to improve the vortex structure inside the pump-turbine for safe and stable operation. The research in this paper can provide reference for the stable operation of the pump-turbine.

Automated summary

Pump-turbines are significant in modern power systems as they ensure power system frequency stability and compensate for the intermittent nature of new energy sources. The study investigates the vortex characteristics and pressure fluctuation intensity of the pump-turbine model operating in pump mode using the Large Eddy Simulation (LES) method. Results indicate that the impeller's wake vortex greatly influences the pump-turbine's internal flow field, originating from the vortex structure near the blade's suction surface. The distribution of trailing edge shedding vortex and shock vortex around the tongue is closely related to the impeller's wake vortex. The research emphasizes the importance of improving the pump-turbine's vortex structure for safe and stable operation.