基于MECST气固相间曳力模型的气体-颗粒团聚物流动特性的数值研究

Numerical Simulation of Flow Behavior of Gas and Particle Clusters Based on Drag Force Model with MECST

由颗粒非均匀流动结构中各个尺度内能量守恒的角度出发,建立了气固两相流系统的整体和局部参数与气固相间曳力的相互关系,提出了基于颗粒悬浮输送能量最小(MECST)气固相间曳力模型;并将其应用于欧拉-欧拉双流体模型中,数值模拟循环流化床提升管内气体-颗粒-颗粒团聚物的流动特性。考察了时均颗粒相密度和颗粒质量流率沿径向的分布;颗粒浓度、提升管压降沿轴向的分布以及颗粒团聚物在提升管内的分布特性。模拟结果表明,颗粒相密度、颗粒质量流率以及提升管压降与实验结果相吻合;与能量最小多尺度气固相间曳力模型的颗粒浓度和颗粒拟温度的结果相比,MECST气固相间曳力模型得到的颗粒浓度较低,从而使颗粒拟温度减小。

The relationship between the parameters and the drag force of a gas-solid two-phase system was established on the basis of multi-scale energy conservation in the inhomogeneous flow of particles.A modified drag force model with the minimal energy consumption for suspending and transporting（MECST） was proposed.By application of the modified drag force model with MECST to the Euler-Euler two-fluid model,the flow behaviors of gas,particles and particle clusters in a circulating fluidized bed riser was numerically simulated.The distributions of the time-averaged solid phase density and the particle mass flow rate along radial direction,and the distributions of the particle concentration,the riser pressure drop and the particle clusters along the axial direction were observed.Compared with the results obtained by energy-minimization multi-scale drag force model,the particle concentration obtained by the modified drag force model with MECST could be reduced,which led to the low particle granular temperature.