基于格子玻尔兹曼方法-离散元法耦合模型的侧喷口喷动床模拟研究

Simulation research on side nozzle spout bed based on LBM-DEM coupling model

气固两相流研究是了解侧喷口喷动床内颗粒剧烈而复杂的运动的有效手段。基于格子玻尔兹曼方法(LBM)-离散元法(DEM)耦合模型,流体相采用LBM中的D2Q9模型,固体相采用DEM软球模型,流固耦合采用Gidaspow模型,从介观角度分析侧喷口喷动床内流动特性,通过模拟和实验验证得到了侧喷口喷动床内流化过程,同时分析了不同喷射速度下空隙率、颗粒水平速度变化、能量分布及颗粒运动轨迹。结果表明:随着喷射速度的增大,管道区域面积也随之增大,时均空隙率范围变大;其动能和势能也增大,但由于初始堆积效应影响,床内颗粒的势能总是大于动能;当喷射速度增加时,床内颗粒势能变化并不明显,而动能变化明显;颗粒在床体内部会形成外循环和内循环2个循环,内循环时流化状态更好。本文结论对后续实验室规模的三维流化床系统快速模拟具有参考价值。

The study of gas-solid two-phase flow is an effective method for understanding the violent and complex movement of particles in the side nozzle spouting bed.Based on lattice Boltzmann method(LBM)-discrete element method(DEM)coupling model,the LBM D2Q9 model is used for fluid phase,the DEM soft ball model is used for solid phase,and the Gidaspow model is used for fluid-structure interaction.From the perspective of mesoscopic side vents in the spouted bed flow characteristics,the fluidization process in the spouted bed with side vents is verified through simulation and experiment.Moreover,the voidage,particle horizontal velocity change,energy distribution and particle trajectories at different injection speeds are analyzed.The results show that,with the increase of injection velocity,the area of the pipeline increases and the range of time average voidage increases.The kinetic energy and potential energy also increase,but the potential energy of the particles in the bed is always greater than the kinetic energy due to the influence of the initial stacking effect.When the injection velocity increases,the potential energy change is not obvious,but that of the kinetic energy is dramatic.Particles in the bed body will form two cycles of external circulation and internal circulation,and the fluidization state in internal circulation is better.The conclusion of this paper has reference value for rapid simulation of laboratory scale threedimensional fluidized bed system.