Solid-liquid multiphase flow and erosion characteristics of a centrifugal pump in the energy storage pump station

Abstract

In order to achieve the goal of carbon neutralization, a new concept of energy storage pump station is proposed, which uses the large pump to store water from the downstream reservoir to the upstream reservoir in cascade hydropower stations, and consumes the electricity from wind and solar power. However, sever erosion of centrifugal pump, which is caused by the high sediment content of rivers, will poses a serious threat to the safe and economic operation of the energy storage pump station. Therefore, it is of great significance to carry out the high precision prediction of pump erosion and reveal the influence of different factors on erosion. In this study, the two-way coupling Euler-Lagrange method is employed to investigate the erosion of a centrifugal pump in the energy storage pump station. Drag model that considers different particle states and erosion model that considers the shape correction are used. The numerical simulation results of erosion in a 90° elbow verify the reliability and accuracy of the erosion prediction approach. Results show that the flow pattern of the liquid plays an important role in the movement of particles and thus influences the intensity of erosion. The particle impact velocity depends on the relative velocity inside the impeller and the absolute velocity outside the impeller. As the flow rate increases, the impact velocity and the number of colliding particles increase, which leads to more severe erosion. The increase of particle density induces the increase of particle Stokes number, and the particles move away from the suction surface, which leads to a reduction of erosion on suction surface. With the increase of coating thickness, the particle diffusion effect caused by the increase of fluid pulsation is greater than the impact effect caused by the increase of flow extrusion velocity, which results in the reduced erosion intensity on the blade. In order to avoid the impact of erosion on the economy of the energy storage pump station, reasonable flow rates and appropriate increase in coating thickness are effective measures.