DSMC-LES方法数值模拟鼓泡流化床内气泡和颗粒流动行为  

Simulating the Flow Behavior of Bubbles and Particles in the Bubbling Fluidized Bed by the Method of Direct Simulation Monte Carlo and Large Eddy Simulation

作　　者：刘欢鹏[1] 刘玉成[2] 李巍[1] 

机构地区：[1]哈尔滨工业大学能源科学与工程学院,黑龙江哈尔滨150001 [2]大庆石油管理局电力集团电调中心,黑龙江大庆163000

出　　处：《高校化学工程学报》2006年第2期180-185,共6页Journal of Chemical Engineering of Chinese Universities

摘　　要：基于稠密气体分子动力学和气固两相流体动力学，建立流化床稠密气固两相离散颗粒运动-碰撞解耦模型，采用直接模拟蒙特卡罗方法（DSMC）模拟颗粒间的碰撞，采用考虑颗粒脉动流动对气相湍流流动影响的大涡模拟（LES）研究气相湍流，单颗粒运动满足牛顿第二定律，颗粒相和气相相间作用的双向耦合由牛顿第三定律确定。数值模拟流化床中颗粒流动以及气泡的生成、长大和破碎过程，获得颗粒轴向和径向速度的概率密度分布，及颗粒浓度分布。计算结果表明床内气泡的形成造成床内颗粒的循环，使得流化床内颗粒具有不同的轴向和径向脉动速度，颗粒分速度分布近似服从高斯分布。颗粒温度随颗粒浓度增加，达到最大值后，随颗粒浓度增大而下降。流化床颗粒浓度脉动主要是低频部分，高频分量较低，表明在流化床内颗粒浓度脉动频率低，能量高，颗粒浓度脉动主频率为0．04～1．0Hz，其值与Pain et al．获得的颗粒浓度脉动主频率基本吻合。For the fluidized bed, based on the dense gas molecular dynamics and the gas-solid two-phase fluid hydro-dynamics of dense gas-solid flow, a discrete particle motion-collision decoupled model was developed. Particle collision was simulated by means of the direct simulation Monte Carlo （DSMC） approach. The large eddy simulation （LES） accounting on the effect of particle fluctuation was used to simulate the gas turbulent flow. The Newtonian equations of motion were solved for each individual particle in the system. The interaction between the gas phase and particles was taken into account by the Newtonian third law. Numerical simulations of the motion of bubbles and particles in a bubbling fluidized bed were performed and the distributions of particle concentration and probability density of axial and lateral velocities were obtained. Simulation results show that bubbles induce the circulation of particles in the fluidized bed in which the distribution of particle velocities can be expressed by the Gauss distribution. With the increase of particle concentration the particle temperature increases and reaches a maximum, then decreases. The domain frequency of instantaneous concentration of particle is in the range of 0.4-1.0Hz, which agrees with the simulation result reported by Pain et. al （2001）.

关 键 词：DSMC方法 大涡模拟 离散颗粒运动-碰撞解耦模型 颗粒温度 

分 类 号：TQ021.1[化学工程] TQ051.13