Time-Dependent 3-D Modelling of DC Transferred Arc Twin Torch

The aim of this work is to investigate by means of a 3-D FLUENT© based numerical model time-dependent effects arising in the fluid flow and temperature distribution of a plasma transferred electric arc discharge generated between two suspended metallic electrodes used inside a plasma furnace for hazardous waste incineration. Flow and energy equations are solved for optically thin Ar plasma under conditions of LTE, while the electromagnetic field equations are solved in their scalar and vector potential form. Electrodes interfaces are taken into account using a simplified approach and their regions are discretized in their detailed design, in order to better understand the effects of their geometries on the discharge behavior. Turbulence effects are taken into account into the model using a RANS approach, as well as the effect on the discharge characteristics of using different types of plasma gas (air and Ar/H2 mixtures), for various geometric and operating conditions. Simulations can also give important information on non-axisymmetric anode attachment under particular operating conditions. Simulations are performed using a customized CFD commercial code, parallelized over a network cluster of double processor calculators in order to use the full capabilities of the 3-D code.