铝粉分散过程中粒径效应的三维数值研究

3D numerical study on particle size effect in dispersion process of aluminum dust

为了研究不同粒径的铝粉在20 L爆炸测试装置中的分散规律,基于计算模型的非结构网格划分,耦合欧拉和拉格朗日方法,实现了描述可压缩气体演化的时间平均Navier-Stokes方程组和粒子运动的DPM动量平衡方程的求解,获得了不同粒径(25,50和100μm)的铝粉在20 L爆炸仓内分散的三维时空演化规律。研究结果表明:铝粉粒径的差异对爆炸仓点火中心的湍动能和速度的演化过程影响不显著,但对粉尘浓度的变化率和峰值均具有重要影响;随着粒径的增大,峰值浓度越小,但均高于形式浓度0.25 kg/m^3,达到峰值浓度的时间越滞后。

To study the dispersion laws of aluminum dust with different particle sizes in the 20L explosion testing apparatus,based on the unstructured meshing of computational model and a coupled Eulerian-Lagrangian approach,both the time-averaged Navier-Stokes equations describing the evolution of compressible gas and DPM momentum balance equation of particle motion were solved,and the 3D space-time evolution laws of dispersion of aluminum dust with different particle sizes(25μm,50μm and 100μm)in the 20L explosion chamber were obtained.The results showed that the difference of the particle size of aluminum dust had no significant influence on the evolution process of turbulent energy and velocity in the ignition center of the explosion chamber,but it had an important influence on both the change rate and peak value of the dust concentration.With the increase of the particle size,the peak concentration became smaller,but all higher than the normal concentration of 0.25 kg/m^3,and the longer time needed to reach the peak concentration.