Melt flow patterns in metallurgical MHD device with combined inductive and conductive power supply

S. Pavlovs¹ , A. Jakoviċs¹ , E. Baake² , B. Nacke²

¹ Laboratory for Mathematical Modelling of Environmental and Technological Processes, University of Latvia, 8 Zeļļu str., LV-1002 Riga, Latvia
² Institute of Electrotechnology Leibniz, University of Hannover, Wilhelm-Busch-Str. 4, D-30167 Hannover, Germany

Abstract
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 hydrodynamic (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 driven by a 3D transient ėxtit{Shear Stress Transport ( SST)} model of turbulence. Several estimations have been performed with a quasi-laminar model; the chosen effective turbulent viscosity is constant. Tables 4, Figs 4, Refs 13.