螺旋轴流泵的固液两相流动数值模拟

Numerical simulation of solid-liquid two-phase flow in screw axial-flow pump

为研究螺旋轴流泵输送含有沙、油和水的固液两相时内部的流动情况,基于Ansys CFX软件,应用RNG k-ε湍流模型,采用固相颗粒直径为2 mm,初始体积分数分别为5%,10%,15%,以及液相油初始体积分数分别为5%,10%,15%时,对螺旋轴流泵叶轮流道内固液两相流场内部变化规律进行数值计算.结果表明:沙和油的分布规律相似,主要集中于叶轮进口边轮毂头部、叶轮外缘区域;当沙和油的初始体积分数改变时,其对应的过流部件内体积分数分布也发生了变化,分布区域也有所改变,说明沙和油两相互相影响对方的分布;当沙和油的初始体积分数一定时,各相的相对速度变化规律总体上趋于一致,其相对速度由大到小依次为沙、油和水;扬程和效率的计算曲线与试验曲线基本吻合,扬程误差值在3%左右,效率误差值在4%左右,说明试验方案的设计合理可行,数值模拟结果较为准确.

To investigate the characteristics of solid-liquid two-phase flow in a screw axial-flow pump,the internal flow field inside the flow passages of the pump were numerically simulated by using Ansys CFX software with the RNG k-ε turbulence model. The diameter of sand is 2 mm,and sand initial volume fractions are 5%,10% and 15%,respectively; whilst the initial volume fractions of oil are 5%,10% and 15% as well. It was demonstrated that sand and oil are mainly accumulated around the leading edge of blade on the hub,and at the impeller tip. If the initial volume fractions of sand and oil are changed,then their distributions in the flow passages are changed simultaneously,and the areas with a higher concentration of them are varied too,indicating that both sand and oil phases can influence the distribution of each other in the flow passages. When the initial volume fractions of sand and oil are kept constant,the relative velocity pattern of every phase in the flow passages generally tends to be consistent with each other. The magnitude of the relative velocity of sand is the highest,but that of water is the lowest,and that of oil is in between. The estimated head and efficiency curves are essentially consistent with the experimental ones because the errors in head and efficiency between estimate and measurement are 3% and 4% only. This suggests that the performance test protocol is reasonable and feasible,and the numerical simulation results are relatively accurate.