稠密气固流动二阶矩摩擦应力模型和模拟

A Second-Order-Moment Frictional Stress Model and Simulation of Dense Gas-Particle Flows

基于统一二阶矩两相湍流应力模型和稠密颗粒动力学理论,建立了欧拉-欧拉双流体二阶矩颗粒摩擦应力模型。模型充分反映各向异性的气固两相相间雷诺应力相互作用,并引入有效颗粒弹性恢复系数,考虑了因颗粒表面不光滑产生的摩擦力对湍流流动结构和颗粒弥散特性的影响,对于下降管的计算结果与实验吻合较好。因颗粒摩擦产生能量耗散降低了颗粒温度和导致颗粒雷诺应力再分布。在入口和出口区域因颗粒碰撞频率较高而产生的能量耗散对流动结构影响明显。

A second-order-moment frictional stress model with Eulerian-Eulerian two-fluid continuum approach is presented on the basis of the unified second-order-moment two-phase turbulence model and the kinetic theory of granular flows. The interaction term between gas-particle turbulence is fully taken into account by the transport equation of two-phase stress correlation. Turbulent flow structure and particle diffusions affected by particle-particle frictional stress are considered by an effective coefficient of restitution due to coarse particle surfaces. Simulation results of downer are in good agreement with experimental data. It shows that particle temperature is decreased by energy dissipation and particle Reynolds stress are redistributed. Furthermore, because of higher parti- cles collisions at the inlet and the outlet; region, the most effect of flows structure are observed distinctly.