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. Parametric studies of the specularity coefficient were performed to evaluate its impact on the predicted gas-solids two-phase flow characteristics in term of S-shaped axial voidage profile, outlet solids flux, local voidage radial profile and local particle axial velocity. The experimental conditions of Fan were simulated and compared with experimental data on the aforementioned characteristics. It were found that the wall boundary condition for solids phase played a much important role in simulating the S-shaped axial voidage profile, and directly affected the capability of capturing the heterogeneous flow structure. A "wall-core-annulus" heterogeneous flow structure, which was significantly different from the commonly known " core-annulus" two-zone structure, could be captured in the bottom of the riser when the free-slip wall condition and EMMS-based model were used together.%引言rn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,国内外学者致力于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.
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