EXCITATION OF WAVES ON A MOLTEN-METAL BY AN INTERMITTENT ALTERNATING MAGNETIC-FIELD

A new process for wave generation on the free surface of a molten meta l is proposed where an intermittent alternating magnetic field with th e stepwise change of amplitude is adopted to induce the time variation of magnetic pressure generating a wave motion. Based on a linear smal l-amplitude wave theory, a mathematical model has been developed, whic h describes the wave motion as a function of operating variables such as intermittent frequency, amplitude of magnetic pressure and vessel s ize. The function is indicated as combination of a free vibration dete rmined by a vessel size and a forced vibration, in which the amplitude of the latter is in proportion to the magnetic pressure difference at the maximum and the minimum magnetic fields. To confirm the validity of the mathematical model, an experiment with liquid gallium was perfo rmed. It was found from FFT analysis of the wave motion measured by a laser level sensor that the frequencies of the wave motion are compose d of an intermittent frequency of the magnetic pressure and the intrin sic frequencies of a vessel. A resonance phenomenon was observed when the intermittent frequency coincided with the intrinsic frequency. Exc ept the resonance case, the amplitude of the wave motion was in propor tion to the amplitude of the magnetic pressure difference. These obser ved results are well predicted by the mathematical model.