背叶片宽度对离心泵水力性能与流场的影响研究

保持叶轮后盖板与泵壳的间隙不变,通过改变背叶片宽度设计出4种不同离心泵叶轮方案。采用CFD仿真模拟对各方案下的模型泵进行了全流道数值计算,得到了背叶片宽度对离心泵外特性与后泵腔流场分布的影响规律。结果表明:背叶片间流道内的低压随其宽度的增加,面积和数值均先减小后增大;后泵腔内的压力梯度过渡均匀,在0.85倍叶轮半径处压力达到最低;当背叶片宽度较小时,叶片间流道内流线基本呈环状,液体流动比较顺畅;背叶片间流道内存在低速区及与叶轮背叶片旋转方向相反的旋涡,背叶片宽度越大旋涡越强烈;背叶片增加了泵的扬程与轴功率消耗,降低了泵的效率,其宽度变化对效率与轴功率影响较大,扬程变化则不明显;研究可为实际工程中控制背叶片宽度提供一定借鉴。

Research on the Influence of Back-blade Width on Hydraulic Performance and Flow Field of Centrifugal Pump

Keeping constant of the gap between back cover plate and pump shell,and four different impeller schemes of centrifugal pump are designed by changing the width of back-blade.CFD simulation is used to calculate the full flow passage of the pump under various schemes,and the influence law of the width of the back-blade on the external characteristics of the centrifugal pump and the flow field distribution of the rear pump cavity is obtained.The results show that the area and value of the low pressure in the back-blade passage decrease first,and then increase with the increase in its width.The pressure gradient in the rear pump cavity is uniform.At 0.85 times the impeller radius,the pressure reaches the minimum.When the back-blade width is small,the streamline in the passage of back-blade is basically annular,and the liquid flow is relatively smooth.There are low-speed vortices in the flow passage of back blades,and vortexes that rotate in the opposite direction to the impeller.The larger the back-blade width is,the more obvious the vortexes are.Back-blade not only increases the pump head and shaft power consumption,but also reduces the efficiency of the pump.Its width has a great influence on the change of efficiency and shaft power,but the variation of head is not obvious.The research can provide a reference for controlling back-blade width in practical projects.