离心泵作透平固液两相流动及磨损的数值模拟

为研究离心泵作透平内部固液两相流动特性,基于Euler-Lagrange模型,应用ANSYS CFX软件对一比转数为82的离心泵作透平进行数值计算,分别模拟颗粒直径为0.1,0.3,0.5 mm及初始体积分数为5%,10%,15%的9组不同工况,以揭示介质中固体颗粒对离心泵作透平运行的影响.计算结果表明:固体颗粒主要分布在叶片吸力面头部、前盖板壁面附近以及蜗壳尾部区域;当固体颗粒质量分数不变时,随着粒径的增大,叶片表面固相体积分数增大,叶片吸力面轮缘处出现了大量颗粒堆积,透平的扬程和功率上升,效率有所下降;当颗粒直径不变时,随着固体颗粒质量分数的增大,固体颗粒在叶轮流道内的分布出现向轮毂处延伸的趋势,堆积区域面积增大,透平的扬程和功率上升,效率变化不大.该研究扩展了液力透平设计方法,可为离心泵作透平设计提供一定的参考.

Numerical simulations of solid-liquid two-phase flows in centrifugal pump as turbine

Numerical simulations were performed on a centrifugal pump as turbine(PAT)with a specific-speed of 82 in ANSYS CFX to investigate characteristics of solid-liquid two-phase flow within the PAT.Nine cases were simulated in terms of particle sizes of 0.1 mm,0.3 mm,0.5 mm and solid vo-lume fractions of 5%,10%and 15%,respectively,by using the Euler-Lagrange model to clarify effects of solid particles on PAT operations.The results show that solid particles are mainly distributed in the blade suction side near the leading edge and the shroud wall as well as in the top wall of cross-sections in the volute.At a constant particle volume fraction,with increasing particle diameter,the solid volume fraction on the blade surfaces is increased and many particles are accumulated on the blade su-ction side.Under the circumstance,the head and power of the PAT get large and the efficiency is decreased to some degree.At a constant particle diameter,with the increase of solid particle vo-lume fra-ction,solid particles in the impeller passages tend to migrate towards the impeller hub,and the accumulation area is expanded.In such a case,the PAT head and power is increased but the efficiency varies a little.The study has expanded design method of hydraulic turbine,and can provide a reference for design of PAT.