梯度磁场下气固流化床中磁颗粒运动数值模拟  

Numerical Simulation of Magnetic Particles Flow Behavior in a Gas-Solid Fluidized Bed with Gradient Magnetic Field

作　　者：李响[1] 孙丹[1] 陈巨辉[1] 王帅[1] 白颖华[1] 陆慧林[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

出　　处：《高校化学工程学报》2010年第1期52-57,共6页Journal of Chemical Engineering of Chinese Universities

基　　金：国家自然科学基金(50776023)

摘　　要：在外加竖直方向梯度磁场的气固鼓泡流化床中,考虑铁磁颗粒受到的梯度磁场力和颗粒间磁感应力,对气相采用流体力学方法(CFD),颗粒相采用离散元法(DEM),建立二维磁鼓泡流化床数学模型,模拟不同磁场强度下全磁颗粒圆形床料的气固流动过程,分析了不同磁场强度对磁流化床中气泡生长、颗粒运动、床层压降和磁颗粒受力的影响。研究结果表明在沿高度磁感应强度递减的梯度磁场中,磁颗粒在颗粒间磁感应力的作用下凝聚成链,破坏了大气泡的形成。随着磁场强度增加,颗粒扩散系数减小,颗粒间磁感应力和梯度磁场力增大;气体与颗粒相间作用力先减小、后增加;而颗粒接触力先增加、后减小。Flow behavior of gas and solids in a two-dimensional magnetically assisted bubbling fluidized bed with whole magnetic balls under vertical gradient magnetic field was simulated. The motion of the gas was simulated by computational fluid dynamics （CFD）, the particles were simulated by using discrete element method （DEM）, and the effects of the magnetic strength in the fluidized bed with the additional magnetic field on the bubbling growing, motion of magnetic particles, gas pressure loss and interaction forces between particles were discussed. The simulation results show that, in the magnetic field with a descending gradient along the fluidized bed height, due to the effect of magnetic induction, the magnetic particles form particle chains which inhibit the formation of big size bubbles; and the particle diffusion coeftTcient decrease with the increase of magnetic field intensity, while the inter-particle magnetic forces and the gradient magnetic force increase with the increase of magnetic field intensity. The drag forces between the gas and particles firstly decrease slightly and then increase with the increase of magnetic field intensity, while the variation of the contact forces between the particles is reverse of that of the drag force.

关 键 词：梯度磁场 磁流化床 气固两相流 数值模拟 流体力学-离散元法(CFD-DEM) 

分 类 号：O359.2[理学—流体力学] TQ051.13[理学—力学]