双吸离心泵变频调速过程中叶轮的径向力特性

Radial force characteristics of impeller during variable frequency speed regulation process of double-suction centrifugal pump

为研究离心泵在变频调节过程中叶轮的受力特性,以某一单级双吸泵离心泵为研究对象,对其在“线性”及“非线性”2种变转速调节规律下泵内流场进行数值模拟,分析变转速过程中叶轮所受径向力及其流道内压力变化.结果表明:不同的变转速过程,转速变化率对径向力变化出现差异起主导作用;2种变转速过程中径向力在圆周方向的矢量分布呈现略微差异,非线性变化时各方向受力更加均匀,更利于设备稳定运行;相比不同时刻所对应的定转速工况,变速工况下径向力均偏大,在0.11 s时刻最为明显,且非线性变化过程径向力值增幅更大,达到534 N;在变频调节过程中,径向力的脉动频率以低频为主;相比于其他部位,叶轮出口的压力变化较明显,引起叶轮出口受力变化,是影响径向力大小的直接因素.

In order to study the force characteristics of the impeller in the variable frequency regulation(VFR)process of a centrifugal pump,a single-stage double-suction centrifugal pump was taken as the research object.The flow field inside the pump was numerically simulated under two types of variable speed regulation laws of linear and nonlinear.The radial force on the impeller and the pressure changes in the flow channel during the variable speed process were analyzed.The results indicate that the rate of change in rotational speed plays a dominant role in the variation of radial force under different rotational speed processes.There is a slight difference in the vector distribution of radial force in the circumferential direction during the two types of variable speed processes.When subjected to non-linear changes,the force in each direction is more uniform,which is more conducive to the stable operation of the equipment.Compared to the constant speed operating conditions corresponding to different times,the radial force under variable speed conditions is relatively large,with the most obvious effect at 0.11 s.Moreover,the nonlinear change process shows a greater increase in radial force value,reaching 534 N.In the process of variable frequency regulation,the pulsation frequency of radial force is mainly low frequency.Compared to other parts,the pressure change at the outlet of the impeller is more signifi-cant,which causes the force change at the outlet of the impeller and is a direct factor affecting the magnitude of radial force.