Research On Particle Materials Motion Analysis In Rotating Drums Based On Similarity

Ball mills,rotary kiln and other rotating drum equipment are widely used in the cement,chemical,mining and pharmaceutical industries.They are mainly used for grinding,mixing,calcining,etc.of materials.The movement of particles in the drum will significantly affect the material crushing effect,mixing quality and other product properties and work efficiency.Since the quantitative information of particle motion in the rotating drum is difficult to obtain by experimental,numerical simulation has been become an important means to study the particle motion in the rotating drum.With the continuous development of industrial rotating drum towards large scale,its internal particle system is constantly expanding,which brings great challenges to the numerical simulation.Although GPU,GGPU,parallel calculation and other conventional high performance and high efficiency computing methods can improve the computing efficiency to a certain extent,the size of the general particle system is difficult to break through ten million,and there is still a huge gap with the actual number of particles in the rotating drum.Thus,researchers have to use reducing the computational system to simulate the actual industrial rotating drum.Common methods include reducing the size of rotating drum and increasing particlesize et al.It is necessary to study the scale effect of particle motion in the rotating drum after reduction,and it is also an effective method to solve the problem of particle size calculation system.In this dissertation,two methods for reducing the size of the particle system in the rotating drum are proposed.The conversion relationship between the scaled model and the physical model's physical parameters and structural parameters is derived,and the relationship is verified by combining experimental and numerical simulation.The main research contents are as follows:(1)The force analysis of the particle detachment process in the rotating drum is carried out,and the interaction relationship between the detacing angle,the rotational speed of the drum,the gravitatinal acceleration and the radius of the drum is established.The scaling relationshaip between parameters of the scaled model and the physical model is deduced.(2)Based on the deduced similarity relationship,a series of experimental schemes were designed,and the experimental platform of rotating drum was developed.Three different sizes of rotating drums were designed and fabricated,and the particle motion in the rotating drum was photographed with a high-speed camera.The trajectories of single particles in different rotating drums and the particle curtain contour formed by multi-particle throwing process were extracted,and the similarity relationship is verified based on this.(3)Taking ABS particles as the research object,the physical properties and contact parameters of ABS were measured by drainage method,scraping method,collision method and contact friction method and so on.The corresponding DEM model was established.Subsequently,a scaled model for reducing the size of the rotating drum and the enlarged particle size was established.Based on the deduced similarity relationship,the parameters of the scaled model were modified and 12 sets of simulations were performed.Finally,the correctness and feasibility of the derived similarity relationship are further verified by comparing the simulation results.