In order to explore the influence of different wear-ring sizes on the performance and flow characteristic in a centrifugal pump, both numerical simulation and performance test are conducted in a centrifugal model pump. Two normal wear-ring clearances(0.25 mm and 0.50 mm)and an abnormal big gap(0.75 mm)are selected. By comparing the pump performance and flow characteristics at every clearance, the influence of wear-ring size on the performance and flow is obtained. It is shown that with increasing clearance both the pump head and the efficiency decrease. The radial thrust on the impeller reaches the largest at 0.50 mm gap, decreases at 0.25 mm, and eventually arrives at the smallest thrust at 0.75 mm. The total pressure is distributed more evenly in the axial cross-section of the wear-ring at a larger clearance. The total pressure near the side chamber decreases, but that near the impeller eye increases. Because of being affected by the centrifugal force on the shroud, the radial velocity magnitude and vorticity of the fluid in the chamber between the shroud and the casing increase gradually with increasing clearance, causing an even more smooth streamline pattern there.
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