Abstract:

In order to analyze the motion laws of particle swarm in vertical converging-diverging tube, the effects of converging-diverging ratio γ, rib height e and particle inlet concentration α on the concentration distribution and convergence characteristics of particle swarm in vertical converging-diverging tube were simulated by the coupled CFD-DEM method. The results showed that the axial concentration of the particle group was relatively uniform, and more particles were retained in the downer part of the tube within the research parameters. The relative concentration of particles in the radial direction followed the rule of low concentration in the center of the tube and high concentration near the wall. When the inlet concentration of particles α≤2%, the particle concentration near the pipe wall was high in the scaler with rib height e=1.0mm. In the relatively stable stage of particle movement in the middle and upper part of the pipe section, when rib height e=2.0mm, scaling ratio γ≤1.0 and particle inlet concentration α≥3%, particle swarm were more likely to convergence.

Key words: two-phase flow, CFD-DEM, particle image velocimetry (PIV), converging-diverging tube, particle convergence, concentration distribution

摘要：

为分析颗粒群在立式缩放管内的运动规律，基于计算流体力学-离散单元（CFD-DEM）耦合方法模拟研究缩放比γ、肋高e和颗粒进口浓度α对管内颗粒群浓度分布与汇聚特性的影响。结果表明：在研究参数范围内，颗粒群的轴向浓度分布较为均匀，管下部颗粒滞留相对较多；颗粒群径向相对浓度遵循管中心区域浓度低，近壁面颗粒相对浓度较高的规律；肋高e=1.0mm的缩放管在颗粒进口浓度α≤2%时，管壁附近颗粒浓度最高。在管段中上部颗粒运动相对稳定阶段，在肋高e=2.0mm与缩放比γ≤1.0、颗粒进口浓度α≥3%工况下，颗粒群易出现汇聚现象。

关键词: 两相流, 计算流体力学-离散单元, 粒子图像测速法, 缩放管, 颗粒汇聚, 浓度分布