基于离散单元法的回转窑物料崩落运动及接触力链研究

Analysis on avalanching motion and force chains of bed material within rotating cylinder based on discrete element method

考虑颗粒物料的离散性质,采用离散单元法建立物料的运动模型,模拟物料的塌落和滚落运动过程,并分析物料颗粒之间的接触力分布及力链结构.结果表明:滚落模式的颗粒相互碰撞剧烈;滑移与塌落的分界线呈幂函数曲线,物料填充率过小易导致滑移;强力链约占力链总数40%,分布在物料底层近90%的厚度区域,而物料表层10%厚度为弱力链区域;塌落、滚落运动中颗粒的崩落主要发生在力链易断裂的弱力链区域;力链近似对数正态分布,切向力是导致力链断裂和表层颗粒崩落的因素.

Considering the discrete properties of granular materials,a kinematic model was developed for the bed materials within a rotating cylinder by the discrete element method.Slumping and rolling process of the granular materials were simulated,and then force chains and distribution of contact forces between particles were investigated.The results show that the particles under rolling patterns have serious collision.Boundary line between sliding and slumping was approximately an exponential curve,and sliding was easily caused by small filling degree.The underlying area of the bed materials（about 90% of the bed thickness）is occupied by strong force chains（about 40% of the total force chains）,and the surface area of bed materials is only filled with weak force chains.In the case of slumping and rolling,avalanches of particles occur mainly in area just filled with weak force chains which are broken easily.The strength of force chains has a Log-normal distribution,and the tangential force in force chain is the factor leading to chain-breaking and granular avalanches.