Numerical simulation of the electromagnetic stirrer adapted by using magnetodielectric composite

Bicakci S., Citak H., Gunes H., Coramik M., Ege Y.

Berga K.K., Berenis D., Kalvāns M., Krastiņš I., Beinerts T., Grants I., Bojarevičs A.

In order to obtain a uniform thermal distribution of a liquid metal melt in e.g. aluminum furnaces, mixing can be provided by rotating permanent magnets. A rotating permanent magnet generates a rotating magnetic field which induces a volume force in the nearby liquid metal. This paper presents a quick-and-dirty experimental and numerical study of temperature equalization with a permanent magnet for a liquid metal volume with a vertical temperature gradient. Thermocouples and a thermal camera have been used to capture the temperature dynamics. The setup consists of a thin walled stainless steel container filled with GaInSn eutectic alloy and a cylindrical NdFeB permanent magnet placed near the side wall. A parametric sweep has been performed by changing the inclination angle of the magnet in order to find the most efficient position for which the thermal balance can be achieved the fastest.

Bolotin K., Brazhnik D.

Paper is devoted to study of the possibility of using a bottom induction stirrer with a rotating electromagnetic field for a force on melt of precious metals in a graphite crucible of an induction crucible furnace. The option of liquid metal stirring after melting is completed to achieve temperature uniformity was investigated. Numerical simulation of three depended problems was carried out: electromagnetic, hydrodynamic, and heat transfer in liquids. The optimization of supply current frequency magnitude was carried out by the Nelder-Mead method; the difference between the maximum and minimum temperatures in the melt volume four seconds after the start of stirring was chosen as the objective function, its minimization was achieved. Range of optimal frequencies of the supply current from 250 to 260 Hz was determined. The most effective frequency is f = 256.2 Hz, with it the temperature difference was ΔT = 8.6 °C. At the next stage, the process of mixing the metal during its melting will be considered.

Bolotin K., Shvidkii E.L., Sokolov I., Bychkov S.A.

Purpose The purpose of this paper is to search optimal shape of soft magnetic composite-based inserts used to compensate the working gap between the liquid metal and the induction stirrer in metallurgical installations. Design/methodology/approach The study was based on numerical simulation of electromagnetic processes in frequency domain. To optimize inserts shape, the Nelder–Mead method was used. The maximum of integral electrodynamic force along x-axis was chosen as the objective function. All simulations were performed in finite element software package Comsol Multiphysics. Findings Optimal inserts shape was determined, at which the value of integral electrodynamic force along x-axis increased by 20% from 692  to 792 N. Originality/value Magnetic concentrators based on soft magnetic composite materials have long been used in high-frequency systems; at the same time, their use in low-frequency systems has not been previously considered in detail. The study of the shape effect of concentrators on the effectiveness of electromagnetic field in a liquid metal in a three-dimensional formulation was carried out for the first time.

Timofeev V.N., Vinter E.R., Khatsayuk M.Y., Fomin A.V., Shakhoval N.S.

This article describes the electromagnetic field analytical model of magnetohydrodynamic (MHD) stirrer with nonsinusoidal current, built with the account of the longitudinal edge effect. The solution is obtained in the form of a Fourier series in a comprehensive way. Differential and integral properties of the system have been defined. There have been received differential and integral characteristics, which are the basis for building the power supply source and control systems for the liquid metal stirring process.

Bolotin K.E., Sokolov I.V., Bychkov S.A.

Shape optimization occupies an important place in the development of MHD-stirrer for liquid metal, allowing to reduce economic and time costs. For all importance and relevance, there is still no unequivocal opinion as to which optimality criterion should be chosen: integral electromechanical force, integral melt velocity or time of technological process, for example, equalizing temperature in the melt volume. Present paper is devoted to comparing results of magnetic core optimization for MHD-stirrer with a traveling EM field for listed optimality criteria. As a parameter, by which efficiency of obtained result was evaluated, the time taken to equalize temperature in the melt volume was chosen.

Dzelme V., Jakovics A., Bucenieks I.

In this work, we study rotating permanent magnet based liquid metal pump. Full 3D model of the pump is created and different approaches to electromagnetic force computation are investigated. First, we seek a possibility to model the permanent magnet block consisting of many separate magnets as a single block with equivalent analytically prescribed magnetization. Second, different approaches regarding coupling of electromagnetic field to fluid dynamics simulation are considered. Main results show that for pump integral parameter calculation, time-dependent coupling is not necessary, although it can lead to different velocity and turbulent structure distribution in the channel.

Frizen V.E., Smolianov I.A., Sarapulov S.F.

The article deals with the design and power scheme of an induction crucible furnace with a capacity of 10 tons for steel from a dual frequency converter. A comparison of dynamics of the melt homogenization process in furnace of the proposed design with a similar process in a conventional furnace is compared. Calculations showed that at the same power, the speed of metal movement in the bath increased more than 6 times, and the rate of temperature equalization increased more than 10-fold due to change in metal flow trajectory in the bath.