U型混合机内颗粒混合运动的离散元模拟

Discrete element method simulation on mixing motion of ellipsoid particles in U-tank mixer

为探究机械搅拌式混合机内分层颗粒混合运动过程,应用离散元法对U型混合机内颗粒径向混合过程和运动规律进行模拟研究,定量分析转速对分层颗粒混合程度的影响。结果表明:U型混合机内对流、扩散和剪切作用机制对颗粒体系混合起着主要作用,颗粒运动存在小瀑布和不规则两种运动形态,颗粒混合系统可分为三个混合区域,三个混合区域之间的颗粒移动交换致使颗粒体系混合均匀,不同转速下各混合区域范围所占比例变化不明显。三种转速下,搅拌轴旋转圈数相同,混合程度相近。

For the study of mixing movement process of segregation particles in the mechanical agitation mixer,three-dimensional discrete element method was used in this research to simulate the radial mixing process and motion law of particles in U-tank and quantitative analysis of the influence between rotating speed and mixing degree of stratified particles.It showed that convection,diffusion and shearing action mechanism had a great influence to particle mixing in U-type mixer.There were two kinds of particle motion patterns,namely cascading and irregularity,and particle mixing system can be divided into three mixing regions.The movement and exchange of these three mixing regions made particles well-mixed while the proportions of the three mixing regions were not changing obviously under different rotating speeds,furthermore,at three rotational speeds,the number of revolutions of the stirring shaft rotates was same and the mixing degree was similar.