前置叶片式叶轮对微型高速离心泵性能的影响

The Influence of Front Vane Impeller on Performance of Small High-speed Centrifugal Pumps

离心泵叶轮进口处回流会降低泵的效率,破坏离心泵运行稳定性。为探求前置叶片式叶轮对离心泵叶轮进口涡量,湍动能,进口回流量及压力脉动的影响,提出了3种叶轮型式:基础叶轮不做改变(方案一),叶轮前盖板处增置直叶片(方案二),叶轮前盖板处增置圆柱形叶片(方案三)。在此基础上结合SST湍流模型对三种叶轮型式的离心泵进行数值模拟。结果表明:与方案一相比,方案二和方案三的扬程和效率在各个工况点都有所提高,口环处回流量降低;方案二叶轮进口附近的涡量区域和叶轮内部湍动能最小,其次为方案三;方案二与方案三在蜗壳内部及叶轮进口处的压力脉动系数基本相同,且均明显小于方案一,说明前置叶片式叶轮可以提高离心泵运行稳定性。

Recirculation at the inlet of centrifugal pump impeller can reduce the efficiency of the pump and destroy the running stability of centrifugal pumps. In order to seek the influence of front vane impeller on vorticity, turbulent kinetic energy, recirculation at the impeller inlet and pressure fluctuation of centrifugal pumps, three impeller types are proposed in this paper： the basic impeller does not change （ scheme 1）, straight blade is added at the front cover of the impeller （ scheme 2）, cylindrical blade is added at the front cover of the impeller （ scheme 3）. On this basis, the centrifugal pumps of three impeller types are numerically simulated combined with the SST turbulence model. The result shows ： compared with scheme 1, the head and efficiency of scheme 2 and scheme 3 are increased at all working conditions and the recirculation of wear-ring decreases. Vorticity region at impeller inlet and turbulent kinetic energy of scheme 2 are minimum, followed by scheme 3. It shows that the front vane impeller can reduce the hydraulic loss and improve the hydraulic efficiency of centrifugal pumps. Pressure fluctuation coefficient at the impeller inlet and within the volute of scheme 2 and scheme 3 is basically the same. They are all obviously less than scheme 3. It shows that the front vane impeller can improve the operation stability of centrifugal pumps.