Variational Multiscale Finite Element Simulation of a Nonequilibrium Atmospheric-Pressure Arc in Crossflow

Abstract

Industrial plasma applications such as wire-arc spraying, lowvoltage circuit breakers and re-entry vehicle testing tunnels require understanding the dynamics of an arc in a cross flow [1]. A canonical atmospheric-pressure arc in crossflow is modeled for the first time using a time-dependent threedimensional (3D) thermodynamic nonequilibrium (NLTE) model. The nonequilibrium plasma flow model is casted as a single transient-advective-diffusive-reactive (TADR) system of transport equations and solved using a Variational Multiscale Finite Element Method (VMS-FEM), which provides a comprehensive and robust formulation suitable for the numerical solution of general multi-physics and multiscale transport problems [2]. The obtained results are validated with prior experimental [1] and computational results based on Local-Thermodynamic Equilibrium (LTE) formulations [3]. Figure 1 shows the arc in crossflow system together with representative simulation results. The established arc strongly interacts with the imposed cold inflow, which causes the arc deflection, convective heat losses, and thermodynamic nonequilibrium. The arc shape is mainly determined by electrode spacing, gas type, imposed total current, and the inflow velocity. The overall effect of the plasma – cold-gas interaction is explored by a non-dimensional analysis.