基于格子玻尔兹曼方法的单孔射流鼓泡床的离散颗粒模拟

Abstract

This paper presents a discrete simulation of bubbling bed with jet flow at a single orifice using a lattice Boltzmann method based discrete particle model proposed by us. This algorithm is based on four-way coupling discrete particle simualtion whereas governing equations of fluid flow solved by modified lattice Boltzmann method with consideration of the effect of porosity and relative slip velocity between particle and fluid and interaction between particles modelled by time-driven hard-sphere model. The EMMS drag model is adopted for coupling between solid and gas phase. We first investigated the influence of particle diameter and gas jet velocity on bubble formation. The results show that bubble size reduces with increasing of particle diameter under the same gas injet velocity, while bubble size increases with increasing of gas jet velocity. Then the relationship of bubble detached from the bottom of bed with particle size and jet flow rate is explored. The results show that with the change of particle size and jet flow rate, bubble detached time is almost the same. We also found that the enlargement of solid initial bed has an effect on bubble size and shape. The bubble tends toward a circular shape with a wider bed of solids and become smaller with increasing of solid initial bed height. Finally we reproduced the phenomenon of bubble inducement that bubble tends move toward an empty region.