循环流化床气固曳力模型

气固曳力是稠密气固两相流动,尤其是垂直流动中的主要作用力,相应的模型也是数值模拟中准确描述气固两相运动的关键.为了解决现有经验或半经验模型的普适性问题,合理描述流动中经常发生的颗粒团聚现象及其对气固曳力的影响,从理论分析入手,运用最小能量的概念,将传统的CFD方法与宏观的系统分析方法相结合,建立了一个新的计及颗粒团聚效应的气固曳力理论模型.与现有模型相比,新模型不仅具有相同的函数变化关系,可合理地描述气固两相相互作用的物理过程,而且避免了以往经验系数不准确导致的各种误差,为稠密气固两相流动的数值描述提供了重要依据.

Theoretical Model of Drag Between Gas and Solid Phase in Circulating Fluidized Bed

Drag force is a key parameter in the analysis of gas-solid flow,especially in dense vertical flows,and is important in numerical simulation of the gas-solid flow.To describe the cluster phenomena and their effects on drag force, a new model of gas-solid drag force is developed under the consideration of cluster effects using the energy minimization concept.Compared with the existing drag models,the new one can reasonably describe the interaction between gas and particle phase,and avoid the error caused by the inaccurate experimental coefficients.It can improve the accuracy of the simulation of dense gas-solid two-phase flow greatly.