Functional Capabilities of Electromagnetic-Acoustic Transformations in Current Mode in the Metal Melt

Abstract

The paper deals with a symmetric problem on the basis of physically substantiated estimates of the processes of electromagnetic-acoustic transformations (EMAT) of energy during the flow of an electric current through a melt and the key parameters of the open problem of the system “Power source parameters–Parameters of the magnetic field and magnetic pressure of the skin layer–Parameters of acoustic disturbances.” When formulating the EMAT problem in technological applications, it was shown that the key parameter is the geometry of the container with the object of processing and the material of the mold. When solving the problem, it is the parameter of the skin layer and the time dependence of the discharge current. It was established that the part of energy during the formation of the magnetic pressure in the skin layer from the amount of the energy stored in the capacitor bank of the pulse current generator is approximately 10^–4–10^–2. The value of this part depends on the period of the discharge current and is proportional to the $\sqrt T$. When acoustic disturbances propagate in the melt, the main share of energy losses is determined by the difference in the acoustic rigidity of the melt and the shape of materials. The frequency spectra of the pressure of sound waves at the parameters selected for the analysis can cover the range of up to hundreds kHz, which is a good reason for the realization of resonance effects and the active formation of dissipative structures. Attention is focused on the fact that the EMAT effects are manifested in the melt not only under the influence of an acoustic field but also under that of an electromagnetic one in the skin layer. They are separated in time, but the acoustic field can occupy the entire volume of the melt and its effect is longer in time.