The Influence of Wear Ring Clearance on Flow Characteristics and Energy Loss in Centrifugal Pumps Based on Multiphase Simulation

Abstract The performance of centrifugal pumps directly affects agricultural productivity and water utilization efficiency, with their hydraulic characteristics being predominantly governed by the wear ring clearance (WRC) and the conveyed medium. At present, studies on the coupled effects of WRC size (dWRC) and sediment-laden flow on the internal flow mechanism of centrifugal pumps are not sufficient. This study aims to quantify the leakage flowrate and flow velocity characteristics at the wear ring, clarify the internal leakage flow characteristics, vortex evolution rules, and energy loss mechanisms of the centrifugal pump under different dWRC and medium conditions. This study employs the simulation with discrete phase model (DPM) to research the flow characteristics in both clear water and sediment-laden water for different dWRC (0.2, 0.6, and 0.8 mm). In addition, the entropy production method is adopted to realize the visualized analysis of energy loss distribution near the wear ring and impeller. An experimental system was specifically constructed for this study to validate the simulation results. The study reveals that the increase in leakage flow caused by the enlargement of the WRC is the dominant factor leading to the degradation of the centrifugal pump hydraulic performance, while the influence of the sediment-laden medium is relatively minor. At the best efficiency point, as dWRC increases to 0.6 mm and 0.8 mm, efficiency decreases by 5.49% and 7.45% in clean water, respectively, and sediment results in an additional efficiency reduction of 0.28% and 0.06%. At the WRC, the distributions of the leakage flow and its induced recirculation zone correspond closely with high entropy production rate (EPR) regions, confirming that leakage flow is the primary source of energy loss. Under the same dWRC, the total velocity at the WRC in sediment-laden flow is 1.28–1.56 m/s lower than that in clean water, which weakens the impact of leakage flow on the main stream. Inside the impeller, vortex-core accumulation areas, streamline distortion zones, and high-EPR regions exhibit strong spatial agreement, indicating that vortex structures are the direct cause of flow instability and energy dissipation. As dWRC increases to 0.6 mm and 0.8 mm, respectively, the total energy loss in the impeller chamber rises by more than 22% and 42% compared with that at dWRC = 0.2 mm, demonstrating that wear ring enlargement exacerbates hydraulic losses by intensifying flow instability. These findings provide a reference for the design of wear rings in centrifugal pumps operating in high-sediment-laden environments and offer important engineering value for improving the reliability of irrigation systems and promoting the development of water-saving agricultural technologies.