(1. 中南大学机电工程学院，长沙 410083；
2. 中南大学交通运输工程学院，长沙 410075；
3. 中南大学建筑与艺术学院，长沙 410083)
摘 要: 针对物料的散体颗粒性质，采用离散单元法建立颗粒物料的运动模型，计算物料在回转窑内的运动与混合过程。通过“颗粒接触数”定义混合指数，分析物料在回转窑内的径向混合。结果表明：模型所得物料的混合形态与实验观测结果相符，回转窑转动6至8圈后，径向混合形态趋于稳定；根据“颗粒接触数”定义的混合指数能更合理地描述物料的混合程度，物料混合指数与时间成指数函数关系；混合速度随回转窑转速的增加而增大，转速越高，混合程度达到饱和所需时间越短，但是所需的转动圈数会增多；转速较低时，混合速度随填充率的减小而增大，但是转速增加到20 r/min后，混合速度随填充料的减小而减小；回转窑转速越高，物料动能的耗散性越强。
关键字: 回转窑；一元物料；固体颗粒；径向混合；离散单元法
（1.College of Mechanical and Electrical Engineering, Central South University, Changsha 410083, China;
2. College of Traffic and Transportation Engineering, Central South University, Changsha 410075, China;
3. School of Architecture and Art, Central South University, Changsha 410083, China）
Abstract:Accounting for the dispersed properties of granular materials, a motion model of granular materials was established using three-dimensional discrete element method, then, the motion and mixing process of material in the rotary kiln were calculated by the model. On this basis, the transverse mixing of granular material within the rotary kiln was analyzed using an improved mixing index which could evaluate the degree of mixing quantitatively. The results, being consistent with the experimental observations qualitatively, show that the transverse mixing becomes stable after six to eight revolutions of the rotary kiln. Mixing index improved on particle contact-numbers can evaluate the mixing degree of material more reasonably. There is an exponential function relationship between the mixing index and time, two kinds of materials have an initial state of complete separation. The mixing rate increases with increasing rotational speed of rotary kiln. Then, the higher the speed is, the shorter the time is needed for material to reach a complete mixing situation, but the number of revolution needed will be more. When the low rotating speed is less than 20 r/min, the mixing rate increases with the decrease of filling lever. The higher the speed, the stronger the kinetic energy dissipated in granular material.
Key words: rotary kiln; mono-disperse material; solid particle; transverse mixing; discrete element method
