离心泵变频调速空化特性数值分析

Numerical analysis on characteristics of cavitation in variable frequency regulation of centrifugal pump

针对某型卧式单级单吸离心泵构建了三维模型,运用计算流体力学理论,采用多参考系模型(MRF)和两相流的混合模型(M ixture)进行模拟,得到水泵内部压力、汽液两相和汽泡相体积分数随电机输出频率和水泵转速的变化规律。计算结果表明:进口低压区的压力与电机输出频率和水泵转速成反比,当其低于汽化压力时,空化必然产生;泵内汽泡相所占的比例与电机输出频率和水泵转速成正比,比例越大,发生空化的概率越大,且越严重。该分析结果符合工程实际,为变频调速在离心泵中得到更好更合理的应用提供了理论依据。

Aimed at a certain type of horizontal single-stage single-suction centrifugal pump,a 3 dimensions mathematical model was constructed.By using the computational fluid dynamics theory and moving reference frame model and two-phase mixture model to simulate the internal state of the pump,the change rule of the interior pressure,vapor-liquid two-phase and vapor-phase volume fraction with the output frequency and the velocity of pump were obtained.The calculation results show that the inlet pressure has the inverse ratio with output frequency of motor and rotation speed,when it is less than vaporization pressure,cavitation is inevitably produced;the relation between volume fraction of vapor-phase and rotary speed is direct ratio.The incidence of cavitation is bigger and more serious with RPM increases.The results can provided a theoretical basis for the better and more rational application of the variable frequency regulation to pump.