摘要：采用离散单元方法 (DEM) 对三维液固流化床进行数值模拟。考虑润滑力的作用, 对比二元混合、窄级配和宽级配3种粒度级配方式对颗粒分布、速度、温度波动和混合程度的影响。分析结果表明:大颗粒有向床层下部运动的趋势, 而小颗粒则有向床层上部聚集的趋势;与窄级配相比, 二元混合和宽级配的轴向速度在不同高度上差异较明显, 且颗粒温度波动也较小, 颗粒更加容易出现偏析;2种颗粒粒径差距越大, 越容易分离, 而粒径越接近, 越难分离, 混合程度越好。

关键词：流化床；多相流；粒度级配；离散单元法；计算流体力学

Abstract：A three-dimensional liquid-solid fluidized bed was numerically simulated by discrete element method (DEM) . The lubrication force was taken into consideration. The influence of the binary mixture, wide size distribution and narrow size distribution on the particle size distribution, particle velocity, particle temperature and particle mixed degree were compared.The results show that large particles tend to move toward the lower part of the bed, while small ones toward the upper part of the bed;compared with narrow size distribution, there are obviously different on the axial velocity of binary mixture and wide distribution in different heights, and particle is lower in temperature and more prone to segregation;the greater the size disparity is between diameter of two particles, the more easily they are separated. On the contrary, the closer the diameter of two particles is, the more difficult they are separated, and thus the better the mixed degree is.

Keywords： fluidized-bed；multiphase flow；particle size distribution；discrete element method；computational fluid dynamics