Numerical Analysis of Plasma Flow with Supersonic Plasma Gun

A multi-physic fields coupling mathematical model was established using fluid controlling equations,heat and mass transfer equations,species transport equations and Maxwell's electromagnetic equations,to predict flow field characteristics inside and outside supersonic plasma gun. The three-dimensional model contained cathode,anode and anode boundary layers,and took ionization and recombination reactions,as well as non-local thermal equilibrium into consideration. The contours of temperature and velocity of plasma jet were displayed under argon and argon- hydrogen working conditions, and arc voltage was also described. The results show that gas temperature inside plasma gun increases by 30%,and velocity increases by 67% after hydrogen was added to working gas. Besides,gas temperature and velocity decrease more sharply at distance of 0~50mm from nozzle exit than that of 50~100mm,while the decrease rate of the velocity and temperature are reduced with increasing axial distance. The relative error of calculated arc voltage is 4.4%,compared with measured value,illustrating the reasonableness of model after considering anode boundary layer.