Numerical Modeling of Free Surface Dynamics of Melt in an Alternate Electromagnetic Field: Part I. Implementation and Ve
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CTION AND FORMER RESEARCH
ONE of the overriding issues of metallurgical industry is to provide metallic materials with enhanced quality and refined engineering specifications (resistance to corrosion, mechanical, electrical characteristics, etc.). Resulting material properties are usually varied with an appropriate additive amounts, and in this respect, it becomes essential to be able to insulate alloy from undesirable admixtures that can be produced on account of chemical reactions with atmosphere and furnace walls, as well as dissolving components of crucible material. Moreover, in order to produce homogeneous material, it is essential to ensure the uniform distribution of alloying particles in a certain time. Among different types of metallic material heating and melting technologies, induction furnaces that ensure contact-less control of electromagnetic (EM) alloy stirring, temperature, and free surface shape are widely applied in metallurgical industry. In industrial Induction Crucible Furnaces (ICF), the melt is usually covered with slag layer (mainly oxides SERGEJS SPITANS, Research Engineer, is with the Institute of Electrotechnology, Leibniz University of Hannover, Wilhelm-Busch Str. 4, 30167 Hannover, Germany, and also Scientific Assistant with the Laboratory for Mathematical Modelling of Environmental and Technological Processes, University of Latvia, Zellu Str. 8, 1002 Riga, Latvia. Contact e-mail: [email protected] ANDRIS JAKOVICS, Associate Professor, is with the Laboratory for Mathematical Modelling of Environmental and Technological Processes, University of Latvia. EGBERT BAAKE and BERNARD NACKE, Professors, are with the Institute of Electrotechnology, Leibniz University of Hannover. Manuscript submitted December 9, 2012. Article published online February 16, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS B
and other light impurities) that acts both as a thermal and a chemical insulator. Instant change of furnace current or frequency can cause free surface instability and slag displacement and lead to undesirable contact between the melt and atmosphere accompanied with chemical reactions and thermal losses. Moreover, severe switches of furnace power may even cause molten metal to splash. Alloying particles usually are scattered on the melt’s free surface during the EM steering process. Because of meniscus shape, the light particles stay on free surface and gather near the crucible walls. The time in which they are forced in melt volume is dependent on the flow intensity and meniscus shape. Hence, optimization of free surface shape appears to be essential in terms of energy performance, system overheating and particle homogenization. Higher power densities are obtained in Induction Furnaces with Cold Crucible (IFCC) (Figure 1). Owing to the air gaps, the sectioned metallic crucible is transparent for EM field and acts as a secondary inductor. In this case, EM pressure prominently squeezes the melt and semi-levitation is achieved. Crucible is cooled by water, and the melt is mainly abutted upon th
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