激光辅助大气等离子弧堆焊射流场计算模型

Calculation model for plasma deposition with an assistant laser effect

使用亚格子尺度模型的正六边形7-bit网格格子Boltzmann方法(LBM)来计算激光辅助大气等离子弧堆焊流场湍流流动,通过选取适当的速度和温度平衡分布函数,对LB演化方程采用泰勒展开、Chapman-Enskog展开及多尺度展开,使平衡分布函数满足一些统计式,并对方程中的微观粒子分布进行宏观统计,最终导出了激光辅助大气等离子弧熔积流场的宏观连续、动量和能量输运非线性偏微分方程,确定了扩散系数和平衡分布函数系数的表达式,为进行等离子弧激光粉末堆焊射流场的模拟作好了准备.

In this paper, the lattice Boltzmann method （LBM） coupled with a subgrid scale model is applied to turbulent flow of the atmospheric plasma deposition with assistant laser effect. The hexigonal 7-bit grid and two opportune equilibrium distribution functions are selected. The LBGK functions are expanded with Taylor expansion, Chapman-Enskog expansion and multi scale expansion. The macro nonlinear partial differential equations of mass, momentum and energy transportation have been derived from statistic of distributions of micro particles in LBGK functions provided the equilibrium distribution functions satisfy some statistic formulas. At the same time, the expression of diffusion coefficients and the coefficients of equilibrium distribution functions are obtained. The erected model is ready for simulation of the atmospheric plasma deposition with an assistant laser effect.