轴流泵内部压力脉动数值预测及分析

基于RANS方程和RNG k-ε模型,采用Ansys-CFX软件对轴流泵泵段进行了多工况三维非定常数值模拟,得到了不同工况下轴流泵内部不同监测点的水流压力脉动值,分析了轴流泵内部不同监测点水流压力脉动的变化趋势,并预测了叶轮进口前由于叶轮转动引起的压力脉动影响范围.通过与实测扬程和效率比较,表明了数值模拟方法的可行性及可靠性.研究结果表明:轴流泵内部压力脉动频率主要受叶轮转动频率控制,较大压力脉动发生在叶轮进口前;叶轮进口处压力脉动从轮毂到轮缘逐渐增大,叶轮出口处压力脉动从轮毂到轮缘先减小后增大,导叶后压力脉动从轮毂到轮缘先增大后减小;小流量工况及大流量工况下压力脉动幅值较最优工况大;受叶轮转动影响,叶轮进口前压力脉动影响至叶轮中心前0.7D左右.

Prediction and numerical analysis for pressure fluctuation of axial-flow pump

Based on RANS equation and RNG k- ε model,Ansys- CFX software was adopted to simulate the 3D unsteady flow of an axial-flow pump sector under different working conditions. The pressure fluctuation value at different monitoring points in the axial-flow pump under different working conditions was obtained,the change trends were analyzed and the influence scope of the pressure fluctuation caused by impeller rotation was evaluated. Compared with the head and efficiency measured,the numerical simulation method was proved feasible and reliable. The results show that the pressure fluctuation frequency in the axial-flow pump is mainly dominated by the impeller rotation frequency,and the larger pressure fluctuation occurs at the impeller inlet. The pressure fluctuation at the impeller inlet increases from hub to shroud gradually and at the impeller outlet decreases first and then increases. However,the fluctuation at the guide vane outlet increases first and then decreases. The pressure fluctuations under the conditions of small flow and large flow are greater than that of the optimal condition. Because of the impeller rotation,the pressure fluctuation affects to 0. 7D of the impeller in front of the inlet.