稠密气固两相流各向异性颗粒相矩方法

基于气体分子动力学和颗粒动理学方法,考虑颗粒速度脉动各向异性,建立颗粒相二阶矩模型.应用初等输运理论,对三阶关联项进行模化和封闭.考虑颗粒与壁面之间的能量传递和交换,建立颗粒相边界条件模型.采用Koch等计算方法模拟气固脉动速度关联矩.考虑气体-颗粒间相互作用,建立稠密气体-颗粒流动模型.数值模拟提升管内气固两相流动特性,模拟结果表明提升管内颗粒相湍流脉动具有明显的各向异性.预测颗粒速度、浓度和颗粒脉动速度二阶矩与Tartan等实测结果相吻合.模拟结果表明轴向颗粒速度脉动强度约为平均颗粒相脉动强度的1.5倍,轴向颗粒脉动能大约是径向颗粒脉动能3.0倍.

ANISOTROPIC SECOND-ORDER MOMENT METHOD OF PARTICLES FOR DENSE GAS-SOLID FLOW

A second-order moment model of particles is proposed in the dense gas-solid flow based on the kinetic theory of granular flow and kinetic theory of gases. The constitutive model of solid phase is closed with the approximated third-order moment enclosure equation of particle velocity from the elementary transport theory. The boundary conditions of velocity and fluctuating velocity energy of particles are proposed with the consideration of the energy transfer and dissipations by collisions between the wall and particles. Interaction between gas phase and solid phase is modeled by Koch (1999) mode. Flow behavior of particles is simulated in a riser. Numerical simulations indicate the distinct anisotropy behavior of the turbulent particles in the riser. Simulated particle velocities, concentration and second-order moments are in agreement with measurements by Tartan and Gidaspow (2004) in a riser. Predicted axial fluctuating energy of particles is on average 1.5 times the mean fluctuating energy of particles, and the axial fluctuating energy is 3.0 times the lateral fluctuating energy of particles.