立式双级自吸泵自吸过程的数值模拟研究

Numerical Simulation on the Self-priming Process of a Vertical Two-stage Pump

针对一台立式双级自吸泵的自吸过程进行气液两相流演化的非定常数值模拟,通过设置泵吸入管空气段和出口管节流阀,相对真实地模拟了立式自吸泵的自吸结构与条件,得到双级自吸泵两级叶轮和蜗壳进出面的静压与含气率变化曲线,分析了自吸过程泵内气液两相流动的演化规律。结果显示,双级立式自吸泵内首级叶轮在自吸过程中起到关键作用,其静压波动较大,做功能力随气水混合物中水的体积分数增大而逐渐加强,并在吸入管中空气全部吸入气液分离室后进入正常排水状态,使次级叶轮进口面静压值稳定,气液分离室含气率随之逐渐下降并使次级叶轮达到正常排水状态,从而完成整个自吸过程。

The self-priming process of a two-stage self-priming pump was studied by the unsteady gas-liquid two phase flow simulation.By setting the air section in the suction pipe and the throttle in the outlet pipe,the self-priming structure and condition of the vertical self-priming pump were simulated relatively realistically.the unsteady pressure and void fraction of two stage impeller and casing were presented,and the evolution of gas-liquid two phase flow of the self-priming pump was analyzed.Results show that the first stage impeller of the two-stage vertical pump play a key role in the self-priming process,the pressure fluctuation is more significant,and the capacity for work increases with the void fraction decreases in the first stage impeller.When all the air in the suction tube is sucked into the gas-liquid separation chamber,the first stage impeller reaches the normal pumping state,and the inlet pressure of the second stage impeller is in a relatively stable state,the void fraction of the gas-liquid separation chamber then decreases gradually and the secondary impeller reaches the normal pumping state,thus the whole self-priming process complete.