Computational study of flow dynamics from a dc arc plasma jet

TL;DR

This study uses advanced 3D simulations to analyze the complex flow dynamics of a DC arc plasma jet, revealing key phenomena such as shear instabilities, temperature deviations, and electric field regions, relevant for plasma technology applications.

Contribution

It introduces a comprehensive 3D simulation framework with a coupled fluid-electromagnetic model to explore plasma jet behavior in detail.

Findings

Identification of jet forcing due to arc movement

Observation of temperature deviations in plasma fringes

Detection of flow instabilities and high electric field regions

Abstract

Plasma jets produced by direct-current (DC) non-transferred arc plasma torches, at the core of technologies ranging from spray coating to pyrolysis, present intricate dynamics due to the coupled interaction of fluid flow, thermal, and electromagnetic phenomena. The flow dynamics from an arc discharge plasma jet are investigated using time-dependent three-dimensional simulations encompassing the dynamics of the arc inside the torch, the evolution of the jet through the discharge environment, and the subsequent impingement of the jet over a flat substrate. The plasma is described by a chemical equilibrium and thermodynamic nonequilibrium (two-temperature) model. The numerical formulation of the physical model is based on a monolithic and fully-coupled treatment of the fluid and electromagnetic equations using a Variational Multiscale Finite Element Method. Simulation results uncover distinct aspects of the flow dynamics, including the jet forcing due to the movement of the electric arc, the prevalence of deviations between heavy-species and electron temperatures in the plasma fringes, the development of shear flow instabilities around the jet, the occurrence of localized regions with high electric fields far from the arc, and the formation and evolution of coherent flow structures.