边界条件和结构尺寸对提升管内气固流动特性的影响

Effect of boundary condition and system structure on gas-solids flow characteristics in riser

引言 提升管是非均匀结构显著的气固两相流动体系,其流动特性主要表现为轴向空隙率的S形分布、径向的＂环-核＂结构以及团聚物的生成和破碎等。近年来,有关数值计算方法的研究增多,其中双流体模型的应用最为广泛,颗粒动理学则是目前封闭控制方程的最合理有效的方法。

A drag model based on energy minimization multi-scale（EMMS）approach was used in the numerical simulation for fast fluidized bed（FFB）containing Geldart A particles.The Johnson and Jackson boundary conditions（BCs）were used for solids phase.The experimental conditions of Li and Kwauk were adopted in the simulation and two inlet BCs were used to evaluate its impact on the predicted gas-solids two-phase flow characteristics in term of axial voidage profile,outlet solids flux and solids holdup.Axial voidage profile was also investigated with different bed diameters and outlet constraints.It was found that it needed less simulation time,and could diminish the cost of simulation for cycle inlet BC than velocity inlet BC.Increasing bed diameter could result in weakened wall influence,and decrease in bed density and heterogeneity of axial profile.The enhancement of outlet constraint could lead to an increase in bed density.