稠密颗粒物质系统鼓泡现象的微观结构研究

Investigation on the microscopic structure of bubble in dense particle system

通过重新整理气相控制方程,实现了基于非结构化网格的离散颗粒与连续流体的非线性耦合求解方法.应用该求解方法模拟计算了二维气固脉冲流化床(pulsed fluidized bed,PFB)单个鼓泡过程,数值计算结果与实验结果相符合.通过剖析两种典型床宽PFB的气固两相微观结构,观察到颗粒起动瞬间力链断裂"解锁"现象和系统压降脉冲现象,发现床内气体的流动是一个由双主涡到多涡共存再到双次涡的发展过程,颗粒的运动呈现三种形态,即抬升,沿鼓泡边界下滑和角落内"滞缓"运动.

An efficient approach for discrete particles coupled with the continuous fluid based on unstructured meshes is developed by reorganizing gas phase governing equations. The bubble formation caused by a single central jet pulse in a two-dimensional Pulsed Fluidized Bed （ PFB ） is simulated. The calculation results show good agreement with the experimental observations. Then our work concentrates on the study of the microscopic structures of two PFBs with different width. Pressure drop pulse and force chain breaks to overcome the inter-particle locking are found just as the jet starts. The simulations show that the gas flows in the bed experience from two-main-vortices to multi-vortices then to two- secondary-vortices. Particles in the bed demonstrate three types of characterized behaviors,i. e. ,raising,downslide along the bubble’s boundary,and creeping motion in the corner.