Novel impeller modification for erosion mitigation and efficiency improvement for renewable energy–driven multistage centrifugal pumps

Currently, a renewable energy–driven deep groundwater pumping and irrigation system with multistage centrifugal pumps at its core is under development. However, solid particles in groundwater, accelerated by the impeller, can cause severe erosion of the peripheral casing, reducing the system's operational longevity and safety. Therefore, this study proposes a novel impeller rear shroud trimming method for erosion mitigation and efficiency improvement. Numerical simulations based on the Euler–Lagrange method and Finnie erosion model align with experimental data. Impeller rear shroud trimming increases the pump efficiency by 5.94 % and the head coefficient by 0.32 under the design condition, and reduces the average erosion rate of peripheral casings by 15.56 %. The trimmed rear shroud redirects some particles into the rear chamber and return vanes, thus reducing radial flow erosion. As the flow rate increases, so does the particle momentum, increasing the probability of particle impact on the casing and weakening the optimization effect. With larger particle diameters, inertial forces dominate, making particles more likely to detach from the fluid and affect the casing, thus reducing the trimming benefits. Moreover, higher particle volume concentrations increase flow disturbances, reducing the trimmed rear shroud's ability to control particle trajectories and mitigate erosion. This study provides an important reference for erosion resistance and performance improvement in multistage centrifugal pump design.