网格尺寸对循环流化床内气固两相流动的影响

将基于能量最小多尺度方法(EMMS)的曳力模型耦合到双流体模型中,并针对循环流化床内的气固两流动进行了模拟研究。采用全滑移壁面边界条件处理颗粒相,考察了3种网格尺度对轴向空隙率和出口颗粒循环量等气固流动特性的影响。计算结果表明,应用EMMS曳力模型处理相间作用力,同时在采用全滑移壁面边界条件处理颗粒相时,双流体模型能够正确预测轴向空隙率分布。采用网格尺寸为2.325 mm×20 mm时,模拟结果和实测数据吻合较好,表明在循环流化床的数值模拟中选择恰当的网格尺度是极为重要的。

Effects of grid size on gas-solid flow in a circulating fluidized bed

A previous version of the energy minimization multiscale(EMMS) approach was incorporated into two-fluid model(TFM) to simulate the gas-solid flow in a circulating fluidized bed with Geldart A particles.The free-slip boundary condition(BC) was used for solid phase.Three grid sizes were performed to evaluate their influence on the gas-solid two-phase flow characteristics in term of axial voidage profile and outlet solid flux.It is found that the TFM can correctly predict the axial profile of voidage with EMMS approach and free-slip BC for solid phase.The outlet solid flux is in an agreement with the experimental data only for 2.325 mm×20 mm grid.This suggests that it is important to adopt suitable grid size in the simulation of circulating fluidized bed.