50IB-32型离心泵汽蚀性能的数值模拟与试验

Numerical simulation and experimental investigations of 50IB-32 centrifugal pump's cavitation

为研究离心泵汽蚀时其内部流动规律,基于Rayleigh-Plesset汽蚀模型和RNGk-ε湍流模型,对50IB-32型模型泵设计工况下汽蚀性能进行全流场数值计算.选择汽蚀发生点、临界汽蚀点以及汽蚀严重点3个工况比较分析叶轮内汽蚀的发展情况.数值计算获得了叶片工作面静压、叶片背面静压以及不同汽蚀余量下叶片背面气泡相体积分布图.计算结果表明:气泡最先出现在叶片背面进口低压区,随着进口压力的降低,气泡开始由进口处向流道内扩展,气泡相在叶片上的分布逐渐增大,在临界汽蚀点时,气泡分布已经扩散到流道内.随着汽蚀程度进一步加剧,气泡相分布向出口方向扩展,严重时气泡充满流道,干扰和破坏叶轮内液体的能量交换,引起汽蚀性能曲线下降.离心泵汽蚀试验结果与数值计算结果相吻合,验证了数值计算的可靠性.

In order to study the internal flow inherence of the impeller when the pump was in cavitation,based on Rayleigh-Plesset cavitation model and RNG k-ε turbulence model,the whole flow passage of 50IB-32 model pump under the design conditions was numerically calculated.The deve-lopment of cavitation in the flow of the impeller was compared and analyzed in primary cavitation,critical cavitation,and serious cavitation.Static pressure distribution on pressure side and suction side of blade and vapor volume fraction of the blade under different NPSH were obtained by the numerical calculation.The results show that bubbles first appear in the low pressure area of the suction side of blade and then extend from the inlet to the main flow as inlet pressure decreases;bubble distribution on the blade gradually increases.In critical cavitation,bubbles extend inside the flow;in serious cavitation,the flow was filled with bubbles,which disturbs and damages energy exchange in the flow and cause overall performance curve to degrade.The results of the experiment agree with the simulation,which validates the feasibility of numerical calculation.