粒子通过管道的尺寸效应

Size effects for particles passing through ducts

研究粒子和管道的特征长度,分析粒子穿过管道的过程,以探讨粒子与管道相互作用的尺度效应。在此过程中,采用粒子覆盖管道截面和粒子填充管道空间的方法,推导出截面覆盖度和管道体积填充度的关系式,计算球形粒子通过圆形管道的相关参数。研究结果表明当管口直径D略小于粒子直径d的2倍时,截面覆盖度最小为25%;当管口直径大于粒子直径的2倍后,覆盖度有大有小,但总的趋势是,随着粒子的直径减小,覆盖度增加;D/d的数量级为102时,覆盖度为86.5%,但当D/d的数量级为105时,覆盖度仍小于90%;在D/d→∞时,覆盖度趋向于1;体积填充度与面积覆盖度具有相似的变化趋势;管口的倒角效应随着D/d的变化而变化,D/d越小,管口的倒角效应越明显。

The nature length of particles and ducts was described, and particles through ducts were analyzed in order to study the size effects of the mutual relations between particles and ducts when particles passed through ducts. In such processes, the relations of covering ratio and filler ratio were defined, and the formulas of internal cutting cover were deduced. The special case of ball particles through cycle ducts was calculated. The results show that the minimum covering ratio is 25% when the caliber is a little less than the double diameter of particles (d). The covering ratio rises and falls after the caliber (D) is more than the double diameter of particles, but the general tendency of covering ratio increases with the decrease of the diameter of particles, and when D/d is equal to 102, the covering ratio is 86.5%; when D/d is equal to 105, the covering ratio is less than 90%; when D/d-> infinity , the ratio tends towards 1. The tendency of covering ratio of filling in the ducts' space with particles is similar to that of covering ratio of the duct in the section. The down-horn effect of caliber changes with D/d, i. e. the smaller D/d, the more obvious the down-horn effect of caliber.