约束条件下粗细混合颗粒动力机理分析

Kinetic mechanism of mixed particles under constraint conditions

混合颗粒的堆积问题一直是自然界以及工业界一个悬而未决的问题。研究的对象是相同密度不同尺寸的两相混合颗粒。通过三维离散元软件PFC3D建立高仿真数值模型并进行离散元数值试验,通过数值模拟和试验对比确定本次研究所用的参数。然后对不同条件斜槽下的颗粒堆积形态进行观察并总结其堆积规律;紧接着进一步测定相同体积条件下均匀颗粒和混合颗粒分别对结构体的动力荷载变化;最终通过研究不同斜槽约束条件下混合粒径条件下的颗粒流的运动情况并得到相应规律性的结果。通过研究发现,混合颗粒粒径条件下的颗粒流运动情况和均匀颗粒粒径条件下的颗粒流运动情况差异较大,颗粒分选对其动能的影响,有约束条件下的斜槽会增加颗粒流的滑程并提高其龙头的速度。该结论对于揭示碎屑流远程特性有一定的参考价值。

Granular materials flow remains an outstanding issue in both nature and industry where typically a range of particle sizes are involved. The mixing and segregation processes of binary granular mixture with particles of identical sizes and with different densities subjected to vertical oscillatory excitation are investigated. The DEM experiments are conducted in the PFC3 D, and the material parameters are fixed through the comparison between the numerical and laboratory experiments. Firstly, the deposition patterns of particles in different constraint chutes are studied. Secondly, the kinetic mechanism between uniform particles and mixed particles is compared, and the regular patterns are revealed. Finally, different kinetic mechanisms of the particles in different constraint chutes are studied, and it is proved that the mixed particles under constraint conditions get more kinetic energies and have a longer runout.