Arc Plasma Torch Modeling

Abstract

Arc plasma torches are the primary components of various industrial thermal plasma processes involving plasma spraying, metal cutting and welding, thermal plasma CVD, metal melting and remelting, waste treatment, and gas production. They are relatively simple devices whose operation implies intricate thermal, chemical, electrical, and fluid dynamics phenomena. Modeling may be used as a means to better understand the physical processes involved in their operation. This article presents an overview of the main aspects involved in the modeling of DC arc plasma torches: the mathematical models including thermodynamic and chemical nonequilibrium models, turbulent and radiative transport, thermodynamic and transport property calculation, boundary conditions, and arc reattachment models. It focuses on the conventional plasma torches used for plasma spraying that include a hot cathode and a nozzle anode.

Effect of the deviation of the current density profile center on the three-dimensional non-transferred arc plasma torch

“…At the cathode surface, the exponential current density profiles were commonly used in the previous literatures [5,23,24,33]. The results obtained by the exponential profiles are proved to be sufficient accurate, but the current density at the end of the profile is not strictly zero.…”

“…Although steady-state simulation can provide sufficient information of the plasma flow field, it is not applied to all circumstances because the real arc always moves on the anode wall and operates in different modes depending on the working conditions. Therefore, time-dependent plasma flow was numerically studied in some works [18][19][20][21][22][23][24], where Trelles et al [22][23] developed a transit model to simulate the arc reattachment by using an artificially high electrical conductivity near the anode wall. The models successfully predict the arc break down and reattachment processes inside the plasma torch.…”

“…In previous works, one can notice that the maximum current density are always located at the center of the cathode tip [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24], particularly for transient models concerning the time-dependent plasma [21][22][23]. Actually, the maximum value of the current density profile imposed on the cathode surface may not be located on the center of the cathode.…”

3D static and time-dependent modelling of a dc transferred arc twin torch system

“…The equations for the 2T thermal non equilibrium model are summarized as follows (see [1,10] for details). Mass conservation and Navier-Stokes equations are the same as LTE model while separate energy equations for the species are needed.…”

“…A lot of modeling work has been done in order to characterize the behavior of transferred arcs in their typical configurations, like free burning arcs or cutting plasma torches [1], but very little has been done in the investigation of transferred electric arc discharges generated between two suspended metallic electrodes in the twin torch configuration. Twin torch generated arcs differ from the other transferred arcs since the anode is not the workpiece, as shown in figure 1, while the arc may or may not pass through a bath of molten material, depending on the specific application or design.…”