Investigation of the Impact of Wear-Ring Clearance on Hydraulic Performance and Axial Thrust in Multistage Low-Specific-Speed Centrifugal Pumps

To address the need for larger wear-ring clearances and the sensitivity of axial forces in novel magnetic levitation pump systems, this study investigates the effects and underlying mechanisms of increasing wear-ring clearances on the hydraulic performance and axial thrust of the single-stage impeller-diffuser structure? the basic component of multistage centrifugal pumps?through numerical simulations which have been validated by experimental data. The results show that the front wear-ring clearance has a significant impact on the pump?s head and efficiency, while the rear wear-ring clearance only affects hydraulic performance minimally. However, both front and rear wear-ring clearances significantly influence the axial force acting on the impeller. Specifically, as the wear-ring clearance increases from 0.1 mm to 0.6 mm, the axial force rises by 203%. Moreover, when the front and rear wear-ring clearances are increased concurrently, the axial force increases at a rate of up to 12.5 kN/mm relative to the wear-ring clearance. Through comparative analysis of cases with different wear-ring clearances, this study elucidates the mechanisms by which increased wear-ring leakage flow impacts the axial force on the impeller in multistage centrifugal pumps. The findings of this work extend current understanding, providing both theoretical insights and practical guidance for the optimization design of magnetic levitation pump systems and for axial load prediction of multistage centrifugal pumps. This research also has significant implications for advancing the magnetic levitation technology in high-speed rotating machineries.