LBM-DEM四向耦合喷动床内介尺度模拟与分析

Mesoscale simulation and analysis of spouted bed with LBM-DEM four direction coupling

研究喷动床内颗粒的流动特性对于喷动床的设计和优化具有重要意义。基于气固两相流流动的LBMDEM四向耦合模型,对单孔射流喷动床中颗粒的流动进行数值模拟。其中,气相采用修正的格子玻尔兹曼方法,颗粒相采用离散单元法,流固之间受力的双向耦合基于牛顿第三定律,颗粒与颗粒及颗粒与壁面的受力双向耦合采用软球模型。模拟得到了流化过程、颗粒与气体的速度分布、床层膨胀高度变化以及床宽对流化过程的影响。结果表明,喷动床内存在强烈的内循环,床宽增加导致颗粒运动能力减弱,射流速度增加使颗粒运动更加剧烈,床层膨胀高度增加。

It is important for the design and optimization of the spouted bed for its design and optimization.This paper developed the LBM-DEM four-directional coupling model based on the gas-solid two-phase flow.And it simulates the flow characteristics of particles in a single-hole jet-spouted bed.The gas phase is dealt with by the modified lattice Boltzmann method and the particle phase by the discrete element method.The bi-directional coupling between fluid phase and solid phase follows the Newton＇s third law.Forces among particles,and between particles and wall are realized by the soft sphere model.The effect of the fluidization process,the velocity distribution of particles and gas,the height change of the bed and the convection process of bed width are abtained.The results show that there is a strong internal circulation in the spouted bed.The increasement of bed width results in the decrease of particles＇ movement ability.The increase of jet velocity makes particles move more violently and the bed expansion height increase.