【摘要】 颗粒材料在低速转鼓中的流动呈现间歇坍塌和连续流动2种流态,当转速提高至临界转速+或降低至时颗粒流态将发生转变,Δ=(+)>0,即存在流态转变的滞后行为。自发现这一现象20多年来,对流态滞后转变机理的探索已成为一个研究热点。本文选取2种不同物性颗粒材料开展低速转鼓中流动状态转变的实验研究,结果显示:当转鼓转速在+和之间时,颗粒的间歇坍塌和连续流动2种流态可以共存。由于颗粒堆积结构对间歇坍塌与连续流动不同运动过程(状态)的记忆效应,流态之间的转变因颗粒结构驰豫特性而表现出滞后行为。更多还原

【Abstract】 Granular surface flow shows discrete avalanches and continuous flow in low-speed rotating drum,and granular system will present a transition between these two flow regimes when the rotating drum is speeded up or slowed down across the critical rotation rates.Experiments reveal that there are two different characteristic rotation rates + and according to rotating speed increasing up and slowing down,respectively,and Δ =(+)>0.This hysteretic transition behavior was found two decades ago,but the mechanism of this phenomenon still lacks a convincing explanation.The authors of the present paper adopt two kinds of granular materials with different properties to explore the hysteretic flow transition mechanism in a thin rotating drum.The results illustrate that discrete avalanches and continuous flow co-exist between + and,and the hysteretic transition of these two regimes are due to the memory effect of jammed packing structures to the flowing states,which serves as spontaneous erratic switches controlling the transition from one regime to the other.更多还原