Effect of Rotating Electrode on Magnetohydrodynamic Flow and Heat Transfer in Electroslag Remelting Process

摘要

A transient three-dimensional (3D) coupled mathematical model has been developed to explore the effect of the rotating electrode on the electromagnetic, flow, temperature fields as well as solidification in the electroslag remelting (ESR) process. Maxwell’s equations are solved by the finite volume formulation. The Joule heating and electromagnetic force (EMF), which are the source terms in the energy and momentum equations, are recalculated at each iteration as a function of the phase distribution. The movement of metal droplets is described by the volume of fluid (VOF) approach. Additionally, the solidification of the metal is modeled by an enthalpy-based technique, in which the mushy zone is treated as a porous medium with porosity equal to the liquid fraction. The rotation speed of the electrode is imposed on the inlet, and the melt rate changes with time proportionally to the Joule heating. The present work is the first attempt to investigate the innovative technology of ESR process with rotating electrode by a transient 3D comprehensive mathematical model. The metal droplets are thrown out by the centrifugal force without enough time to grow up in the process with rotating electrode. The melting rate increases because of the enhanced heat transfer in the vicinity of the electrode tip. With a 800A current, the melt rate increases from 0.0078 kg/s to 0.0114 kg/s, while the rotation speed ranges from 120 rpm to 160 rpm. Besides, the metal pool not only keeps the same depth, but also becomes wider in spite of a higher melting rate.