稠密气固两相流中颗粒团运动的DEM模型研究

颗粒聚集成团是稠密两相流动中的基本现象．本文直接以颗粒团为研究对象,建立了颗粒团运动的DEM软球模型,具体给出了稠密气固两相流中颗粒团大小的计算表达式,建立了非球形颗粒团运动、接触碰撞及破碎模型,并将此模型用于模拟一循环流化床内稠密气固两相流动,得到了流化床内颗粒团详细的运动碰撞经历及浓度、粒径分布,所得结果合理,与前人实验值相符．另外,计算表明,采用颗粒团运动的DEM软球模,能使计算量有效减少,计算时间明显缩短,说明本模型可有效地用于工程意义上的稠密气固两相流问题的模拟。

STUDYING OF CLUSTER BEHAVIOR IN DENSE GAS-PARTICLE TWO-PHASE FLOW BY USING DEM MODEL

Most Particles are congregated as clusters in dense particle-gas two-phase flow. In this paper, the particle cluster Discrete Element Method (DEM) is proposed by treating particle cluster as one discrete phase. The models established include calculation expression of the cluster instant size, the irregularly shaped cluster motion, collision, break-up and reforming models. These models are used to numerically study the two-phase flow in a CFB (Circulating Fluidized Bed), and detailed results regarding the dense two-phase flow characteristic in this CFB are obtained. These results are reasonable and are agree with previous experimental ones. The computational memory and computational time are effectively reduced. These calculated results show that this method is feasible and can be used to study the two-phase flow in a CFB efficiently.