摘要:
提出了在圆形滚筒内设置十字形内构件的增混方式,并采用离散单元方法对设置不同大小内构件的滚筒内非等粒径二元颗粒体系的混合进行了数值模拟试验.通过模拟结果重点分析了内构件对混合的影响,讨论了内构件的尺寸对混合效果的作用,分析和探讨了滚筒内构件对二元颗粒体系的增混机理.研究发现,当滚筒内无内构件时,对流、扩散和离析三种作用机制对颗粒体系的混合和分离都起到了重要作用;当滚筒内含内构件时,颗粒的混合则只受到颗粒对流和扩散机制的作用,而颗粒的离析效应得到了很大程度的抑制.十字形内构件很大程度上会破坏滚筒内的自由表面流,从而使发生在自由表面流中的颗粒分离不能发生,最终可有效地增加颗粒之间的混合.对于采用在滚筒内设置十字形内构件的方式来增加颗粒间的混合,存在一个最优的内构件尺寸,内构件过小或过大都不利于颗粒间的混合.
Abstract:
Cross shaped baffles are set in the horizontal drum to augment mixing of the size-type binary particles, and the discrete element method was employed to study the mixing of the size-type binary granular systems in the rotating horizontal drums with different sized cross shaped baffles. The influences of the baffle and the size of the baffle on the mixing were discussed. The mechanisms of the augmenting of mixing of the baffles were discussed in this paper. The simulation results show that the convection, the diffusion and the segregation controlled the mixing and demixing of the binary granular systems in the rotating horizontal drum without baffle. When the baffle was set in the drum, only the convection and the diffusion operated, and the segregation of the binary particles were suppressed, because the cross shaped baffles can break the free-surface flow in the drum and the segregation of the binary particles in the free-surface flow can not occur, and the mixing can be enhanced. An optimum size of the baffle exists for the augmenting mixing of the size-type binary granular systems in the drum with baffles. The oversized and undersized baffles are unfavorable for the mixing of binary particles in the drum.
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