双吸泵系统开阀过程瞬态特性数值模拟

Numerical Simulation on Transient Characteristics of Double-suction Centrifugal Pump System during Opening Valve Processes

采用SST-SAS湍流模型,对一双吸离心泵闭式系统中泵启动和阀门开启两阶段的瞬态流动进行非定常数值模拟,研究了瞬态扬程、蜗壳内压力脉动及叶轮径向力等瞬态特征的变化规律。结果表明:泵启动阶段的瞬态扬程预测值与试验结果吻合良好;与稳态计算结果相比,瞬态开阀过程流动模拟所得扬程预测值与试验结果更为接近;不同开阀时间对泵的瞬态特性有重要影响,随着开阀时间增加,泵的瞬态流量明显增加,瞬态扬程变化不大;开阀过程中,蜗壳上各监测点的压力脉动呈周期性变化,其频率主要为叶片通过频率,蜗壳隔舌处压力脉动幅值变化最为剧烈;叶轮径向力随阀门开度增加而减小,在叶轮旋转周期内,叶轮径向力呈现以叶片通过频率为主频的周期性变化规律。

The unsteady numerical simulations were carried out to investigate the transient flow features of a centrifugal pump system at startup and valve-opening processes. The scale-adaptive simulation（ SAS）based on SST turbulence model was used in the simulation. The computational domain was the entire closed double-suction centrifugal pump test rig. The transient head of the pump,the pressure pulsation on the casing and the radial force on the impeller were focused on. The results showed that the predicted transient head of the pump in startup processes agreed well with the experimental data. Compared with the steady-state calculations,the transient valve-opening simulation produced a pump head which was more close to the experimental data. The transient flow rate increased significantly with the increase of valve-opening time,while valve-opening speed almost did not affect the transient head. During the valveopening process,the pressure pulsation on the volute changed cyclically,the dominant frequency equaled to the blade passing frequency. In addition,the most dramatic change in pressure pulsation amplitude was found in the region near the tongue. The radial force on the impeller decreased with the increase of the valve opening size,and it changed with the blade passing frequency.