口环间隙泄漏对离心泵空化性能的影响分析

以DG-350型多级离心泵次级叶轮为研究对象,研究了口环间隙对离心泵空化性能产生的影响。通过定常数值模拟,计算出了离心泵的扬程和效率,同时得出了口环与进口段交汇处的速度矢量图、涡量云图和空化区域分布图以及叶轮流道内的空化区域分布图。模拟结果与实验结果的对比分析表明:(1)误差都在实际工程所要求的5%左右,说明计算与模拟结果准确;(2)由于口环与进口段交汇处速度旋涡的存在,使得离心泵的进口段与前口环交汇处区域的压力降低,从而导致了空化现象的发生;(3)随着口环间隙的增大叶轮流道上的空化区域也随之增大,从而减小了流体的过流面积,使流体速度和必须的汽蚀余量增大,NPSHR增大,则叶轮进口处的空化区域也就会增大。

Influence of wear-ring clearance on cavitation characteristics of centrifugal pumps

Taking the secondary impeller of DG-350 multistage centrifugal pump as a test model, the influence of wear-ring clearance on the cavitation performance of the centrifugal pump was studied. The head and efficiency of centrifugal pump were calculated by steady numerical simulation. The velocity vector, vorticity distribution and cavitation area distribution at the intersection of wear-ring and inlet as well as the cavitation distribution in the impeller channel were obtained. Compared with the simulation results and experimental results, the errors were all about 5% of the engineering requirements, the calculation and simulation results were accurate. Due to the existence of velocity vortices at the intersection of the wear-ring and the inlet section, the pressure at the intersection of the inlet section of the centrifugal pump and the front wear-ring clearance decreased, resulting in cavitation. With the increase of wear-ring clearance, the cavitation area on the impeller channel also increases. Thus, the flowing area reduces, the fluid velocity and NPSHR increase, and then the cavitation area at the inlet section of the impeller increase.