末级密封间隙对自平衡多级离心泵性能的影响

摘要

为了阐明不同末级密封间隙值变化对自平衡多级离心泵性能及其流动特性的影响,以某型号的自平衡多级离心泵为研究对象,基于泵的几何参数,建立4组不同末级密封间隙值的匹配方案,通过CFD软件对不同方案进行全流场数值模拟,并与试验结果进行对比分析.研究结果表明:随着末级密封间隙值的增加,不同工况下整泵的扬程和效率逐渐减小,泵高效点向小流量点偏移;同时在设计工况下,低压区从首级泵腔向次级泵腔移动,次级泵腔的压力梯度明显,而首级泵腔的压力梯度减弱,导致泵的首级轴向力不断增大,次级轴向力先减小后增大,总轴向力大小增加,方向指向首级叶轮进口.%In order to clarify the effect of variation in value of different final-stage seal clearance on the performance and flow characteristics of self-balancing multistage centrifugal pump,four sets of matching schemes of final-stage seal clearance values were established with the self-balancing multistage centrifugal pump as the research object and based on geometric parameters of the pump,the numerical simulation of the whole flow field was carried out by the CFD software and was compared with the test results. The research results show that the head and efficiency of the whole pump under different working conditions decreases gradually and the high-efficiency points shift to small flow points with the increase of final-stage clearance value,at the same time the low pressure area moves from the first-stage pump chamber to the second-stage pump chamber,the pressure gradient of second-stage pump chamber is obvious,whereas the pressure gradient of first-stage pump chamber is weakened under the design point conditions,which lead to continuous increase of the axial force of the first stage and axial force of the second stage decreases first and then increases and the total axial force increases and directs to the inlet of the first-stage impeller.