Time Dependent 3D Large Eddy Simulation of a DC Non-Transferred Arc Plasma Spraying Torch with Particle Injection

The aim of this work is to investigate by means of a 3-D time-dependent numerical model the plasma flow and heat transfer inside a DC non-transferred arc plasma torch op-erating at atmospheric pressure [1-6], using a customized version of the CFD commercial code FLUENT©. Unsteady flow and heat transfer equations are solved with coupled electromagnetic ones, for an Ar optically thin plasma un-der conditions of LTE. Cathode and anode regions are taken into account in a simplified way, neglecting the non equilibrium effects of the sheath region. The attachment and detachment of the discharge on the anode wall as a result of the drag of the flow field is predicted, without any external enforcement on the placement of the new attach but imposing an uniform zero potential condition on the wall. Turbulence effects are taken into account by means of a Large Eddy Simulation (L.E.S.) approach, solving the dynamic behavior of the larger scale eddies outside the torch nozzle [7]. Prediction of particle trajectories and thermal history is performed in the time dependent framework, in order to predict the effect of the cold gas entrained eddies on particle behavior. Simulations are performed over a network cluster of double processor calculators due to the large computational requirements of the unsteady model and the grid refinement needed for the turbulence model in a full 3-D environment