The water flow and sand particles motion in a prototype of doublesuction centrifugal pump were simulated using the RNG k-ε turbulence model and the Euler-Lagrange multiphase flow model. The influence of length and relative position of the back vanes on sand mass concentration around the wearrings and pump efficiency were analyzed. According to the predicted results, the flow models adopted in this paper can predict the water flow pattern and the sand concentration near the wearrings precisely. The velocity of water flow near the wearrings is so low that the flow carries less sand particles away from the entrance to wearrings, causing there exits a much high sand concentration near the rings compared with the bulk sand concentration in the flow. Eventually the two surfaces of the wearrings gap are damaged quite quickly.With decreasing length of back vanes the pump efficiency is degraded and there exits a minimum length for back vanes to prevent sediment erosion in the wearrings. When the number of backvanes is reduced to three from four, the ability for flow to carrying sand particles is retained and its protecting effect on the wearrings the impeller rings is significant. Further, the pump efficiency is kept in a reasonable level. The case 7 is the optimal design of the blade vanes.
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