双叶片离心泵内动静干涉的三维PIV测量

3D PIV measurements of rotor-stator interactions in double-blade centrifugal pump

为研究叶轮与蜗壳的动静干涉作用,采用三维PIV对一双叶片离心泵最优工况下叶轮流道内3个截面内的流动进行了测量,每个截面内测量9个叶片位置.结果表明:随着叶片与隔舌距离的不同,叶轮流道内的相对速度场和轴向速度场发生了明显的变化;当叶片在隔舌与蜗壳1断面间时,流道内的流量最小,相对速度场分布最为均匀;在前盖板附近吸力面的流道出口出现了低速区,形成了射流-尾迹结构,并在流道进口发现较强的轴向速度;当叶片随着旋转方向远离隔舌时,流道内的流量逐渐增大,在叶片压力面进口出现了流动分离并产生了旋涡,而流道出口的相对速度变得平稳,同时流道进口的轴向速度减弱;当叶片随着旋转方向靠近隔舌时,叶轮流道内的流量逐渐减小,流道进口的旋涡减弱并消失,流道出口的压力面附近相对速度降低,吸力面附近的相对速度增大,同时流道进口的轴向速度继续减弱.

In order to study the impeller-volute interaction in a double-blade centrifugal pump, the flow in three sections of impeller passages was measured with nine different locations between a blade and the tongue of volute at the best efficiency point. The relative velocity field and axial velocity field are greatly dependent on the distance between a blade and the tongue. When a blade is between the tongue and the section 1 on volute, the flow rate in that passage is the lowest, and the relative velocity field is uniform. Meanwhile, there is a low velocity zone in the corner between the shroud and the blade suction side at the passage outlet, causing a jet-wake flow pattern at the impeller outlet. A hi- gher axial velocity range is observed at the passage inlet. As the blade leaves far away from the tongue due to its rotation, the flow rate in the passage is increased, and flow is separated from the blade pre- ssure side, establishing a vortex there. The relative velocity profile at the passage outlet becomes uni- form, and the axial velocity at the passage inlet decreases as well. As the blade gets close to the tongue, the flow rate in the passage is reduced, and the scale of the vortex is decreased and disappears eventually. The relative velocity at the blade pressure side outlet is lowered, but that at the blade suc- tion side is increased, meanwhile the axial velocity at the passage inlet continues decreasing.