基于CFD技术的双吸式离心泵转轮副叶片优化

应用Fluent软件,基于RNG k-ε湍流模型和欧拉-拉格朗日多相流模型,对双吸式离心泵内的水流和泥沙颗粒运动进行了模拟,分析了不同长度、不同相对位置的副叶片对口环保护和水泵效率的影响.结果表明：选择的模型可准确地模拟双吸式离心泵内部流场和口环部位泥沙质量浓度,口环附近流速较低,对泥沙颗粒的挟带能力较弱,造成口环附近泥沙质量浓度远远高于水中平均泥沙质量浓度,导致了口环处快速磨损;缩短副叶片长度,能有效减小水泵装置效率的降幅,副叶片长度为1/4叶片长度时,靠近口环区域水流的相对速度的径向分量比较小,副叶片不能有效减小泥沙对口环的磨损;副叶片数由4减为3时,水流的挟沙能力得以保持,对口环的保护效果仍然明显,同时还能有效减小水泵装置效率的降幅;通过对比分析,方案7中的副叶片既能减小泥沙对口环的磨损,还能有效地减小由于副叶片的存在导致的圆盘摩擦损失,因此,选择方案7为最终优选方案.

Optimization of impeller back vanes in double-suction centrifugal pump by CFD technique

The water flow and sand particles motion in a prototype of double-suction 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 wear-rings 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 wear-rings precisely.The velocity of water flow near the wear-rings is so low that the flow carries less sand particles away from the entrance to wear-rings,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 wear-rings 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 wear-rings.When the number of back-vanes is reduced to three from four,the ability for flow to carrying sand particles is retained and its protecting effect on the wear-rings 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.