细颗粒泥沙对离心泵工作特性影响的数值研究

A Numerical Study of the Impact of Fine Sand-particles on Centrifugal Pump Working Characteristics

基于Eulerian-Eulerian"双流体"模型观点,应用CFD软件Fluent对离心泵细颗粒泥沙固液两相流进行了数值模拟。给出了在微米量级尺度上不同粒径及10%颗粒体积浓度以内条件下离心泵固液两相流动规律,得到了相应的离心泵的外特性的变化规律并与清水单相流情形进行了对比。研究结果表明:在叶轮流道内,固相体积浓度分布极不均匀,细颗粒主要集中于流道出口处及叶轮吸力面。在所研究的工况条件下,与清水情况相比,加入某些浓度、粒径的细颗粒离心泵内的湍流黏度,湍动能都有所下降,并且分布规律与颗粒的分布相似,离心泵的扬程与效率有所提高。相同体积流量下,离心泵的扬程和效率在所研究的工况条件下随颗粒浓度和粒径的增加先增大后减小。

In order to study the turbulence modulation mechanism due to the fine sand-particles in pumps, three-dimensional simula- tions are performed for the dispersed solid-liquid two-phase turbulent flow in a centrifugal pumps by using Fluent CFD software based on Eulerian- Eulerian two-fluid model. The solid-liquid two-phase turbulent flow fields in pumps have been simulated for the fine sand-particles of micron-size with the volume fraction less than 10 %. The two-phase calculation results are compared with those only with single phases, i.e. clean water. It is concluded that： in impeller channels, the volume fraction contour is extremely non-u- niform, showing that solid particles mainly accumulate on the suction side of each impeller. With regard to the working conditions in the study, after certain fine sand-particles with certain volume fraction are added, while having the similar distribution of solid parti- cles the turbulent viscosity and turbulent kinetic energy all decreases compared with the clean water single-phase flow, and the head and efficiency of pumps are improved. For the simulated cases, the head and efficiency of pumps increase first, then decreases with the increase in fine sand-particle size and volume fraction.