Numerical Modelling of an Anodic Metal Bath Heated with an Argon Transferred Arc

Abstract

A new 3-D model has been developed to describe the interaction between a transferred electric arc and a liquid metal bath, and has been used to simulate a pilot axisymmetrical transferred arc furnace operating in the EDF Research and Development laboratory.This model enables calculations of the flow patterns, temperature distribution and electromagnetic fields in both the arc and the bath. The Navier-Stokes equation coupled with the electromagnetic relations are solved in each domain using a finite volume method. The source term in the radiative energy equation is modeled using the radiative transfer method in order to take into account the strong temperature variations in the electric arc. The transport and condensation of metal vapour in the arc domain are considered by solving a conservation equation for the vapour mass fraction. The arc flow calculation at the bath surface uses a one-dimensional sheath model taking account of the metal vapour, in order to ensure the coupling between the plasma and the bath by evaluating the boundary conditions at the arc/bath interface. The calculations were performed for an arc length of 0.25 m.Realistic predictions are obtained for the electrical, dynamic and thermal behaviour of the plasma and liquid metal, and also for the arc voltage. The results indicate that the effects of the arc impact and Lorentz forces are not sufficient to induce effective mixing throughout the metal bath, leading to a marked thermal stratification in the liquid metal. In the bath, the liquid/solid interface has been determined by calculations.

Three-Dimensional Unsteady MHD Modeling of a Low-Current High-Voltage Nontransferred DC Plasma Torch Operating With Air

“…The restrike mode is characterized by a highly unstable movement of the arc where the reattachment phenomenon plays a significant role. The first models were two-dimensional (2D) or 2D axisymmetric thus, the vortex inflow and the arc root attachment could not be perfectly reproduced [7], [19], [20]. With the improvement of computing power, many research teams moved towards threedimensional models which are closer to real configurations [4].…”

“…With computing power improvement, models get more and more sophisticated and close to real conditions thus allowing today the simulation of three-dimensional and unsteady systems with detailed geometry description. Numerous fluid models have been reported in the literature mostly on direct current (DC) arc discharge modeling using Digital Object Identifier high current above 100 A [1], [2] including: free burning arcs [3], [4], transferred arcs [5]- [7] and non-transferred arcs [8]- [11]. Many DC arc plasma torches models have been developed for different applications [12] as: cutting [13], welding [14], deposition and spraying [8]- [11], [15], [16], steelmaking [7], waste disposal [17] and ultra fine particle production [18].…”

Influence of Plasma Heating on the Metallurgical Effects of a Continuous Casting Tundish

“…The working gas (argon) is flushed from the hollow part of the electrode and ionized into plasma under the action of an electromagnetic field, forming arc plasma, which converts electric energy into heat energy and dynamically heats the molten steel. At present, the ability of plasma to heat molten steel in tundishes has been generally accepted [10][11][12][13], and numerous scholars [14][15][16][17] have carried out simulation research on the plasma heating process. Barron-Meza et al [18] studied the influence of the plasma heating position and flow control device on the flow and heat transfer of molten steel in a tundish by means of physical simulation and numerical simulation.…”

Comparative study of pressure-correction and Godunov-type schemes on unsteady compressible cases

“…It is also crucial to be able to deal with compressible flows for the safety studies in the nuclear power-plants (for instance: steam-water flows in the primary circuit or complex gas mixtures in the containment). The present paper has been motivated by a safety study on a large electrical power transformer involving a compressible flow with a very large energy source term independent of density [6], [7]. Indeed, under specific conditions, an electric arc may strike, accompanied by a very strong and local Joule effect heat source term (typically 10 10 W m −3 ) and by a modification of the fluid properties at high temperature (typically 30, 000 K): the flow becomes locally compressible and the pressure rise resulting from such conditions may deteriorate the structure of the power transformer.…”