基于同轴直管和倒置锥形管的氩大气压等离子体射流放电形态的实验和仿真

摘要

为了研究同轴直管和倒置锥形管对氩气大气压等离子体射流(APPJ)放电形态的影响,首先进行实验,并通过建立二维轴对称模型,耦合求解连续性方程、Navier-Stokes方程、k-ε湍流方程和粒子质量输运方程,数值仿真两种管体中的氩气流的摩尔分数分布.相关结果表明,层流状态下,直管中的放电沿着管壁发展且不稳定;倒置锥形管中放电稳定,且集中在管体轴部.在层流状态下,与传统的同轴直管相比,采用锥管能够改善氢气流场分布,管体内存在较低氩气摩尔分数形成的薄层,阻碍了沿面放电的发生,保证了放电的稳定性.而湍流状态下,由于径向扩散效应,两管体中氩气摩尔分数分布差异变小,等离子体放电的形态差异不大.%In this paper,the Ar atmospheric pressure plasma jet (APPJ) generated with coaxial straight tube and inverted tapered tube was experimentally investigated at first,and then the Ar mole fraction distribution inside both tubes was simulated numerically with two-dimensional axis-symmetrical models.The continuity equation,Navier-Stokes equations,k-ε turbulence equation and species mass transportation equation were coupled and solved.The results showed that,in laminar flow,the discharge developed along the inner wall of straight tube unsteadily,but along the central axis of tapered tube stably.Compared with straight tube,the tapered tube could improve Ar mole fraction distribution in laminar flow.A thin layer,composed of air and argon with low fraction,hindered the discharge along the inner surface,which maintained the stability of the discharge.While the argon was in turbulent flow,due to radial diffusion,the Ar mole fraction distributions inside both tubes were identical,and thus the discharge differed little.