高比转速混流泵时变湍流特性分析

Analysis on Time-varying Turbulent Flow Characteristics of High-specific-speed Mixed-flow Pump

为分析混流泵内部流场的时变湍流特性,采用时变不可压牛顿流体的控制方程和RNG k-ε湍流模型,基于ANSYS CFX软件数值计算了3种不同工况时混流泵内部的时变湍流场,计算考虑了各过流部件间的相互干涉作用。在叶片安放角0°时,给出了最优工况1.00QBep有、无叶轮时进、出口干涉面的静压分布云图,直观地显示了一个物理周期内动静干涉情况,分析了叶片表面流动的细部结构,并对比了基于时均流场和时变流场预测泵外特性的差异。进、出口断面静压分布受叶轮旋转的影响很明显,流量1.46QBep时进口断面静压表现出较强的非稳定性,扭矩和扬程呈周期波动。

The time-varying turbulent flow performance of a mixed-flow pump was simulated by ANSYS CFX soft using the un- steady incompressible flow governing equations and the RNG k-ε turbulence model. The interaction between pass-flow parts was taken into consideration. The static pressure distributions on the interaction surface were given at the optimum operating condi- tions that blade angle was zero and without blade ,which show respectively the variation of flow field characteristics in the impel- ler, and full flow passage in one rotating cycle. The wall streamline of blade suction side was analyzed. The difference of external characteristics between time-averaged and time-varying calculation results was compared. Static pressure distribution is effected obviously by impeller rotating in inlet and outlet section,especially at flow ratel. 46QBep ,Static pressure distribution of inlet sec- tion takes on instantaneity, head and torque on the impeller, of which fluctuations are periodic.