Non-Equilibrium Modeling of Arc Plasma Torches

TL;DR

This paper develops a two-temperature non-equilibrium model for simulating DC arc plasma torches, showing improved accuracy over equilibrium models in predicting arc behavior and plasma flow dynamics.

Contribution

The paper introduces a detailed non-equilibrium model that eliminates the need for reattachment models, providing more accurate simulations of arc reattachment and plasma flow.

Findings

Non-equilibrium model predicts larger non-equilibrium regions.

Improved agreement with experimental data.

Differences in arc reattachment dynamics and voltage drops.

Abstract

A two-temperature thermal non-equilibrium model is developed and applied to the three-dimensional and time-dependent simulation of the flow inside a DC arc plasma torch. A detailed comparison of the results of the non-equilibrium model with those of an equilibrium model is presented. The fluid and electromagnetic equations in both models are approximated numerically in a fully-coupled approach by a variational multi-scale finite element method. In contrast to the equilibrium model, the non-equilibrium model did not need a separate reattachment model to produce an arc reattachment process and to limit the magnitude of the total voltage drop and arc length. The non-equilibrium results show large non-equilibrium regions in the plasma - cold-flow interaction region and close to the anode surface. Marked differences in the arc dynamics, especially in the arc reattachment process, and in the magnitudes of the total voltage drop and outlet temperatures and velocities between the models are observed. The non-equilibrium results show improved agreement with experimental observations.