采用改进的曳力模型模拟2D鼓泡流化床的流化特性

A Modified Drag Model Used for CFD Simulation on the Fluidization Characteristics of 2D Bubbling Fluidized Bed

针对特定颗粒浓度范围颗粒团聚作用导致的曳力下降问题,基于传统曳力模型在不同颗粒浓度段的特性分析,选择适用于不同颗粒浓度区间的曳力模型,通过光滑函数得到改进的曳力模型,并耦合欧拉双流体模型对2D鼓泡流化床进行数值模拟.结果表明,与Gidaspow和Syamlal?O'Brien模型相比,改进的曳力模型对床层局部压降的预测结果更好;随表观气速增加,改进的曳力模型能更准确地预测床层膨胀;当表观气速Ug?0.46 m/s时,改进的曳力模型对径向颗粒浓度分布的模拟结果明显好于Syamlal?O'Brien模型.

Based on the characteristic analysis of existing drag models for different particle concentration segments, three traditional drag models, which are adaptive for specific concentration ranges, are chosen for the drag force reduction caused by particle agglomeration. The smooth function is used to connect the drag models, then a modified drag model is proposed. Coupling with the Eulerian-Eulerian model, the modified drag model is applied for simulation of 2D bubbling fluidized bed. The result shows that the modified model has better prediction of partial pressure drop than Gidaspow and Syamlal-O’Brien models. Along with the increase of superficial gas velocity, the modified drag model can predict more accurately bed expansion. When Ug-0.46 m/s, the modified model leads to a better simulation result of particle concentration than Syamlal-O’Brien model apparently.