Large eddy simulation is performed on a circulating fluidized bed (CFB) based on an Eulerian-Eulerian approach. The riser of the CFB has two axial sections of different diameters joined by a diffuser. The effects of drag and subgrid-scale models are examined on hydrodynamic parameters, such as solids volume fraction (${\epsilon }_s$), solids circulation rate ($G_s$), and full loop pressure profiles. A hybrid energy minimization multi-scale (EMMS) drag model is applied that combines EMMS drag models for the bubbling and the fast fluidized bed regimes. Experiments are conducted on a pilot-scale CFB model, and numerical results are validated against the experimental measurements of pressure and $G_s$. The change in the riser diameter has a significant influence on axial- and radial profiles of ${\epsilon }_s$, particularly in the upper riser section. The hybrid EMMS drag model and the sgs-TKE turbulence model give the best agreement to the experimental data.

基于欧拉-欧拉方法在循环流化床 (CFB) 上进行大涡模拟。CFB 的立管具有由扩散器连接的两个不同直径的轴向部分。检查阻力和亚网格尺度模型对流体动力学参数的影响，例如固体体积分数（${\epsilon }_{秒}$), 固体循环率 ($G_{秒}$)，以及全回路压力曲线。应用混合能量最小化多尺度 (EMMS) 阻力模型，该模型结合了用于鼓泡和快速流化床制度的 EMMS 阻力模型。实验是在中试规模的 CFB 模型上进行的，数值结果根据压力和$G_{秒}$. 立管直径的变化对立管的轴向和径向剖面有显着影响。${\epsilon }_{秒}$，特别是在上立管部分。混合 EMMS 阻力模型和sgs -TKE 湍流模型与实验数据最吻合。