Abstract:

Particle-wall collision and particle-gas interaction have significant influence on the separation performance of the impact separators. The experiments were carried out to study the particle-wall collision behaviors. A particle-wall collision model with average restitution coefficient was proposed. The restitution coefficient and friction coefficient were described as a function of collision angle, and this function varies for different particles. The shape of particles was measured by microscope. The glass beads are very close to sphere, while the coal particles are quite irregular. Thus spherical particle drag force model was adopted for glass beads, and non-spherical particle drag force model was adopted for coal particles. The numerical investigations on the separation performance and gas-solid flow in the plate-type impact separators were conducted with the particle-wall collision model and non-spherical drag force model. The simulation results show good agreements of both overall and grade separation efficiency with the experimental results. The separation prediction of particles with large Stokes number is sensitive to the particle-wall collision model, while that of particles with small Stokes number is sensitive to the particle-gas drag force model.

Key words: separation, granular flow, computational fluid dynamics, particle-wall collision model, non-spherical particle drag force model

摘要：

颗粒-壁面撞击行为和气固相间作用对撞击分离器的性能具有重要影响。基于玻璃珠及煤粉的单颗粒撞击实验数据建立平均撞击恢复系数模型，采用非球形颗粒曳力模型对平板式撞击分离器的分离性能和气固流动开展数值研究。结果表明，采用基于实验的平均恢复系数模型以及考虑颗粒形状的曳力模型，能够准确地预测撞击式分离器的总分离效率和分级分离效率。颗粒分离过程中，Stokes数较大的颗粒对颗粒-壁面撞击模型比较敏感，Stokes数较小的颗粒对气固曳力模型比较敏感。

关键词: 分离, 颗粒流, 计算流体力学, 颗粒-壁面撞击模型, 非球形颗粒曳力模型