不等粒径流化床的硬球模拟

Hard-sphere Simulation with Unequal Particle Diameters in Gas-solid Fluidized Beds

实际工程中,气固流化床中固相颗粒的直径满足一定的分布规律,但近年来颗粒轨道模型的研究中颗粒直径并不满足一定的分布规律.基于颗粒轨道模型,提出了粒径服从均匀分布(正态分布)的硬球方法;改进了颗粒碰撞搜索技术;模拟了单孔、双孔、三孔分布板中气泡的形成、上升、破裂过程以及流化床中的节涌现象;研究了粒径分布不同时,固相颗粒的速度分布规律.研究结果表明:分布板的结构对气泡行为有明显影响;宽粒径分布的颗粒轴向速度大于窄粒径分布的颗粒轴向速度.

In the engineering, particle diameters are obeyed some distribution rules in gas-solid fluidized beds, but which isn＇t obeyed in previous studies of the particle-motion-resolved model. Based on the particle-motion-resolved discrete model, a hard-sphere method used for the simulation of fluidization is established in which particle diameters are obeyed uniform distribution or normal distribution. In our model, the particles motion is dominated by using the Newton＇s second law, and fluid motion is described by the Navier-Stokes equation. At the same time, the searching strategy of particle collision is also improved. The above-mentioned method has been used for simulating bubbling And the distributive rules of solid velocities are and slugging behaviors in the fluidized beds. studied when distributions of particle diameters are different. Simulation results indicate that the structure of distributor has distinct influences on the bubbling behaviors. Moreover, the axial solid velocities of wide distribution for different particle diameters are bigger than that of narrow distribution.