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The article deals with the study of the heating and melting process for the industrial scale direct current electrical arc furnace (DC EAF). Numerical modelling was performed using the enthalpy and porosity approach at equal values of metal solidus and liquidus temperatures when the mushy zone is represented by the linear distribution of the mass fraction. The heat flux supplied through the arc spot is estimated using the heat balance equation taking into account metal heating and melting, Joule heat, radiation at the metal mirror and convective heat transfer at the metal vessel covered with firebricks. Electrical parameters of the arc between the top electrode and the melt mirror are estimated using the heat flux value. Computed distributions of the metal liquid/solid mass fraction make it possible to estimate duration of heating and melting. [ABSTRACT FROM AUTHOR]

The present paper details a comparison of experimental and computational results for the electrovortex flow of mercury in cylindrical and semi-cylindrical vessels, which is driven by the direct electrical current supplied over top and bottom non-submerged electrodes. The time-averaged velocity of liquid metal computed using the LES model of turbulence qualitatively and quantitatively agrees with the measured profiles of the axial velocity for a cylindrical experimental setup. For a semi-cylindrical setup which represents possible "cold" physical modelling of MHD devices, the observed flow patterns at the free surface and the computed flow patterns also agree qualitatively. [ABSTRACT FROM AUTHOR]

The paper presents the computations results on the turbulent electrovortex flow and temperature field in the melt and the results on the concentration field of alloying additive in an industrial-scale (3.6 t of molten steel) electrical arc furnace with direct current power supply over one top and two bottom electrodes. The developed and experimentally verified numerical model is applied. The Large Eddy Simulation model of turbulence is used. The influence of complicated geometry (vertical blades) of the bottom electrodes on electrovortex flow regimes is compared with that of electrodes of conventional geometry. Melt flow patterns near the electrodes' blades are also observed at the melt mirror for the developed laboratory-scale experimental setup (4.8 kg of GaInSn). Melt homogenization is considered for: (i) the temperature field when the heat flux from the arc is injected at the arc spot zone at the melt mirror; (ii) the concentration field when the mass flux of alloying additive is introduced at a chosen zone of the melt mirror. [ABSTRACT FROM AUTHOR]

Controlling of electrovortex flows of liquid metal in a confined vessel is an essential feature of electrometallurgical technologies and aggregates, such as stirring, welding, electroslag remelting, electrical arc furnaces, etc. In the present study, the numerical model developed by the authors in previous studies has been improved to compute turbulent velocity and temperature fields for electrovortex flows of liquid metal in an experimental setup with the bifilar direct current supply over two fully submerged electrodes. Melt velocity and temperature fields were measured by applying a thermal-correlation method. The measured and computed results were compared. A good qualitative and quantitative agreement between the experimentally obtained data and the numerical computation results for the velocity field in several setup zones was found. [ABSTRACT FROM AUTHOR]

Electrovortex flow of liquid metal in a vessel relates to melt stirring in electrometallurgical processes and aggregates, such as welding, electroslag remelting, electrical arc furnaces and others. Maximum values of electromagnetic force and flow velocity develop in the zone between or under the electrodes, where sophisticated 3D flows are formed. In the paper, examples of electrovortex flows near two fully submerged electrodes with bifilar DC supply are discussed. The measured electrical potential and 3D self-magnetic field compared with results of numerical calculation and with a quasi 2D model of EM fields are discussed. Numerically computed 3D electrovortex flow patterns are presented for two regimes, i.e. (i) laminar and (ii) turbulent obtained with the LES approach. There is good qualitative and quantitative agreement between experimental data, analytical and numerical computation results, as well as with some previously published results. [ABSTRACT FROM AUTHOR]

This paper focuses on numerical analysis of the dynamics of boron removal from the molten silicon surface by blowing oxidizing gas during refinement. The aim of the investigation is the estimation of the mass transfer coefficient of boron and studying its dependences on (i) the intensity of molten silicon circulation driven by an alternating current in a coil around a cylindrical crucible, (ii) the geometry and location of lance(s) and on the oxidizing gas supply parameters of the injecting system. The gas-silicon interface is assumed fixed and chemical reactions are not considered. Results of computations are presented for laboratory-sized and scaled models. [ABSTRACT FROM AUTHOR]

The paper presents a numerical study of metallurgical magnetohydrodynamic (MHD) devices with combined power supply: i) inductive by an alternating current (AC) coil; ii) conductive through electrodes with AC or direct current (DC). Peculiarities of the Lorentz force computations are discussed for the following cases: i) the interaction of inductive or conductive currents with their self magnetic fields; ii) the cross effect of the interaction between the current and the magnetic field produced by different sources; iii) the phase shift between inductive and conductive currents. The developed 3D models for computations of electromagnetic (EM) and hydro-dynamic (HD) fields are presented for the ladle furnace (LF) with an EM stirrer. A three-phase conductive current is supplied to electrodes submerged into the melt. An inductive current is supplied by a side non-symmetrical inductor, which is the source of a travelling magnetic field. Melt flow patterns are obtained also for an axisymmetric MHD device. The conductive single phase AC supplied to the top electrode submerged into the melt and to the bottom electrode is the source of electro-vortex convection (EVC). The inductive single phase AC supplied by an almost cylindrical coil (each winding has a thin gap) placed around the melt is the source of EM convection (EMC). Melt circulation is the results of the competition between EVC and EMC. MHD rotation appears due to the cross effect of the current-magnetic field interaction produced by different sources. The melt flow is computed by a 3D transient Shear Stress Transport ( SST) model of turbulence. Several estimations have been performed with a quasi-laminar model; the chosen effective turbulent viscosity is constant. [ABSTRACT FROM AUTHOR]

The paper presents new results of the long-term computations of turbulent flow and low-frequency oscillations of the temperature field in the industrial induction channel furnace (ICF) with a widened channel branch and different iron yoke positions. The computations of turbulent heat and mass exchange in the melt are performed using a 3D transient Large Eddy Simulation (LES) approach. A 3D electromagnetic (EM) model was used for Lorentz force density computations, which act as a source term in the Navier-Stokes equations of the melt flow. The distributions of alloying additions into the melt and disjointed impurities due to channel erosion are discussed for a symmetrical ICF and an ICF with one widened branch of the channel. Cloud distributions and particle trajectories are obtained using a Lagrangian approach along with LES modelled velocity and thermal fields. A long-term analysis of the particle transport for industrial ICFs has been performed for the first time. [ABSTRACT FROM AUTHOR]