异径混合非球形颗粒在移动床中流动特性的数值模拟

Numerical simulation of flow characteristics of non-spherical particle mixture with different diameters flowing in moving bed

为了研究非球形颗粒在移动床内的流动特性,采用多元颗粒模型模拟了异径玉米形颗粒、异径椭球形颗粒以及异径圆柱形颗粒在移动床中的流动情况.探讨了异径混合球形和非球形颗粒在移动床中流动时的流型、概率分布特性以及空隙率分布情况.结果表明:异径球形颗粒在下料过程中由整体流逐渐向漏斗流转变,而异径非球形颗粒从下料开始即为漏斗流;异径球形颗粒及非球形颗粒的概率密度分布中均只有一个峰值,其对应的速度不同;异径圆柱形混合颗粒的空隙率波动范围最大,平均空隙率也最大;异径混合非球形颗粒的直径比越大,平均空隙率越小.

To study the the flow characteristics of non-spherical particles in the moving bed,a multi-element particle model was developed to simulate the corn-shaped,ellipsoidal and cylinder particles flowing in the moving bed.The flow patterns,probability densities and voidage distributions of spherical and non-spherical particle mixture with different diameters in the moving bed were studied.The results show that the flow pattern of the spherical particle mixture with different diameters changes from mass flow to funnel flow gradually,while that of the non-spherical particle mixture with different diameters exhibits funnel flow from the very beginning.The probability density has only one peak value for spherical and non-spherical ones,but the corresponding velocity values are different.Both the fluctuation range and the mean voidage of the cylinder particle mixture with different diameters are the largest.For the non-spherical particle mixture with different diameters,the mean voidage becomes smaller with the increase of the diameter ratio.