Rupture of Thin Film Covering the Liquid Metal Stirred by Alternating Magnetic Field. Numerical Simulation

Abstract

The present work deals with the technological process of induction melting of heat-resistant nickel alloys and, in particular, with the problem of formation and stability of oxide film on the surface of the melt. Our mathematical model describes the heat and mass transfer in the metal melt subjected to the influence of an alternating magnetic field, and the elastic stress states of the film on its surface. The governing equations of the problem are given and non-dimensional parameters are discussed. It is shown how the influence of the magnetic field strength on the flow of the metal melt changes at different frequencies. The states of the surface film are studied theoretically using numerical simulation. It is shown that the variation of the field strength at different frequencies leads to decaying oscillations in the velocity field. The causes of these oscillations are discussed in detail. The stress and destruction of thin films by melt motion are considered. The mechanisms responsible for the primary destruction of the initial film and its fragments are revealed. The rupture of quasi-stable films at different frequencies is studied. It is shown that the result of the influence on the film state with the increase of the magnetic field strength depends on the field frequency. The frequency range was found in which the surface film is strong enough to prevent the intensification of the melt flow with the increase of the magnetic field strength, this effect provides the stability of the film.