Physico-Chemical Modelling and Numerical Simulation of an Inductive Plasmatron

Abstract

This contribution report on the development of numerical models of the inductive plasmas at sub-atmospheric pressures in the 1.2 MW Plasmatron wind tunnel constructed at the von Karman Institute. This facility will serve as an experimental means of testing thermal protection systems installed on space vehicles to protect them during the atmospheric (re-)entry phase of their flight. Numerical models are being developed to cover design and fundamental theoretical issues. As a first step in the development, the flow inside the plasma wind tunnel is assumed to be in a state of local thermodynamic equilibrium (LTE). This assumption is valid only at near the atmospheric pressure. The thermodynamic properties of a chemically reacting mixture of gases under LTE are determined by means of statistical mechanics. The transport coefficients of an ionised mixture of gases in the collision-dominated regime are computed through the Chapman-Enskog spectral Sonine solution of the Boltzmann equation. Mixture rules suited for inductive plasma conditions are referred to. Results are shown for the thermodynamic and transport properties of air and other gases; comparisons are made with numerical and experimental results of other researchers. An LTE model of the inductive plasmas inside the plasma torch of the VKI Plasmatron wind tunnel is presented. The governing MHD equations for the specific case of inductive plasmas are given. The discretisation method and the iterative solution procedure used in the model are described. Numerical results are given for an argon inductive plasma at 1 atm