蜗壳断面面积变化规律对双吸离心泵水力性能的影响

针对某泵站S700-500-730型双吸离心泵运行时引发的断轴问题,采用CFD数值模拟方法,通过与蜗壳断面面积线性变化规律(以下简称L-规律)进行对比,分析了原型泵采用的蜗壳断面面积变化规律(以下简称Y-规律)对水力性能以及径向力的影响.结果表明:在定常工况下,2种规律的双吸离心泵在设计工况下水力性能相近,相较于L-规律方案,采用Y-规律设计的蜗壳作用在叶轮上的径向力增大高达24.77%;在非设计工况下,相较于L-规律方案,采用Y-规律设计的蜗壳水力性能更加优越,但是作用在叶轮上的径向力要高于采用L-规律方案时作用在叶轮上的径向力;在非定常工况下,Y-规律方案的脉动幅值以及高频脉动都要比采用L-规律方案设计时明显得多.蜗壳断面面积变化规律对作用在叶轮上的径向力影响显著.研究结果可为解决由于径向力过大导致断轴问题提供一定的理论依据.

Influence of volute cross-sectional area profile on hydraulic performance of double-suction centrifugal pump

Aiming at the problem of shaft breakage caused by the operation of S700-500-730 double-suction centrifugal pump in a pump station, the CFD numerical simulation method is used to analyze the influence of the volute cross-sectional area profile on the hydraulic performance and radial thrust. The original profile(Y-law)adopted in the pump is compared with the volute cross-sectional area li-near profile(L-law). The results show that the pumps with two kinds of volute cross-sectional area profiles share a similar hydraulic performance at the design point, the radial thrust in the pump with Y-law profile is increased by 24.77% compared with the pump with L-law profile. Under off-design conditions, however, compared with the pump with L-law profile, the hydraulic performance of the pump with Y-law profile is more superior, unfortunately, the radial thrust on the impeller is higher than the former.Under unsteady flow conditions, the pulsation amplitude and high frequency pulsation of radial thrust in the pump with Y-law profile are much more severe than the pump with L-law profile. The variation rule of volute cross-sectional area has a significant influence on the radial thrust ac-ting on the impeller. The results can provide a theoretical basis for solving the problem of shaft brea-kage caused by excessive radial thrust.