Efficient fully implicit and equilibrium finite volume model of induction plasma tunnels.

In this paper a finite volume model of an inductively- coupled plasma wind tunnel (plasmatron) is presented. The model considers arbitrary gas mixtures in chemical equilibrium and computes the composition from statistical thermodynamics. Radiative losses can be taken into account in the form of equivalent gray body emission. The scheme directly solves for temperature instead of for internal energy without additional computational effort. This removes the costly need to solve for equilibrium composition and temperature from internal energy and reduces the CPU time devoted to chemistry The numerical efficiency in terms of speed is further improved by using a fully implicit solver for both the inner cells and the boundary conditions. The method is validated against a supersonic flow in a conical nozzle. Very good agreement has been obtained. Performance characteristics of the VKI plasmatron, as predicted by the present code, are presented, notably two-dimensional charts (mass flow rate, total enthalpy) and chamber pressure required to obtain supersonic flow conditions.