两级中开泵级间隔板对双吸叶轮径向力的影响

Influence of baffles in second stage suction chamber on impeller radial force in two-stage centrifugal pump with axial split case

为研究两级中开泵双吸叶轮所受径向力,基于SST k-ω模型分别对原型泵和加入隔板后的两级中开泵进行数值模拟,获得了泵外特性、螺旋形压水室和双吸叶轮截面上的静压分布及作用在双吸叶轮上的径向力特性.研究结果表明:试验与数值计算外特性曲线趋势一致,表明建立的两级中开泵计算模型是可靠的;级间流道内隔板结构对二级压水室内部的静压影响不大,而双吸叶轮内部静压变化比较明显;隔板对外特性影响比较明显,加入隔板后扬程提高了9%~16%,效率最高增幅约为5%;在一个周期内不同工况下,叶轮所受径向力呈明显的规律性分布,即十角星分布,说明叶轮上径向力矢量分布跟叶轮与蜗壳的动静干涉作用相关;两级中开泵在0.6倍设计工况下径向力最小但不为0,在设计工况下有隔板结构的两级中开泵双吸叶轮所受径向力小于原型泵.

To study impeller radial force in two-stage centrifugal pump with axial split case, two pumps, one is a prototype pump and one is with baffles in the second stage suction chamber, were in- vestigated numerically by CFD software based on the SST k -ω turbulence model. The pump perfor- mance and static pressure distribution in the mid-span plane of the volute of the second stage were ob- tained, and the characteristics of radial force acting on the double suction impeller of the second stage were calculated. The results show that the numerical predictions are in good agreement with the experi- mental measurements. There is no notable difference in static pressure distribution within the volute of the second stage across two pumps, and the pressure distribution in the double suction impeller varies obviously from one pump to another. The baffles in the suction chamber of the second stage have an evi- dent effect on the hydraulic performance. The head of the pump with baffles is about 9% - 16% hi- gher than the pump without baffles, and the hydraulic efficiency is improved by around 5% in maxi- mum. All the radial force are distributed regularly, as a decagram, demonstrating the radial force vector distribution around the impeller is related to the interaction of impeller and volute. Meanwhile. the ra- dial force on the double suction impeller reaches the minimum at 0. 6Qd operation point, but non-zero, and the radial force in the pump with baffles is lower than that in the prototype pump at design point.