Analysis of solid-liquid two-phase flow and sediment erosion during centrifugal pump shutdown process

In order to study the characteristics of solid-liquid two-phase flow and sediment wear during the shutdown of centrifugal pump, based on the calculation results of transient flow in pumping station system, the bidirectional coupled Euler-Lagrangian method and Oka erosion model were used to calculate and analyze the sediment wear of different particle sizes during the shutdown of centrifugal pump. The calculation shows that in the early stage of shutdown, the flow rate is large and the flow pattern is stable. The particles with different particle sizes have little influence on the flow field in the centrifugal pump. With the decrease of flow rate, the flow pattern of the internal flow field is disordered. The particles with two particle sizes have different flow characteristics, and the flow field distribution is slightly different. The wear analysis shows that the impeller area of the centrifugal pump has the most serious wear, and the wear mainly occurs at the outlet of the blade pressure surface near the upper cover plate. With the decrease of the flow rate, the sediment carrying capacity of the water flow decreases, the solid particles migrate downward, and the wear position moves down synchronously. Among them, the wear rate of small particles increases with the decrease of the flow rate, and the wear rate of large particles does not change much. When the flow rate is small, the vortex in the flow channel causes the particles to swirl and hit the middle of the blade, resulting in local wear. In the guide vane area, both particles will impact the leading edge of the guide vane. The small particles are greatly affected by the flow field. With the movement of the water flow, the wear in the middle of the guide vane near the inlet is large, while the large particles are less affected by the flow field. The particle trajectory changes, and the wear mainly occurs at the leading edge of the guide vane. At small flow rates, the vortex between the guide vanes will aggravate the wear of the guide vane surface. The vortex at the outlet of the suction chamber leads to greater wear at this place ; in the volute, the wear is distributed in a spiral shape at large flow rate ; when the flow rate changes rapidly, the flow field around the tongue becomes unstable, which induces local wear in the region.