Three-dimensional modelling of the flow and heat transfer in a laminar non-transferred arc plasma torch

By experimental observation we show that the plasma flow and heat transfer within a direct current (DC) non-transferred arc plasma torch always show appreciable three-dimensional (3D) peculiarity even when the geometrical construction of the torch and working gas admission and external electrical collection conditions are completely axisymmetrical. Previous two-dimensional (2D) modelling studies cannot predict the 3D peculiarity of the plasma torch. We have successfully performed 3D modelling, and in this paper we present the modelling results for the plasma flow and heat transfer characteristics in a laminar DC non-transferred arc argon plasma torch. The predicted arc-root location on the surface of the torch anode and arc voltage compare favourably with the corresponding experimental results.