Modeling of the turbulent flow in induction furnaces
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UCTION
FLUID flow and transfer processes in industrial metallurgical installations became the subject of numerical modeling many years ago. Nevertheless, the absence of a universal and always reliable modeling approach, together with a wide choice of available nonuniversal turbulence schemes, turned it into a nontrivial problem, up to now. Melting of alloys in induction crucible furnaces can be mentioned as a widespread example, because this process can be approximated with a two-dimensional (2-D) axialsymmetric model. The flow pattern in these installations is formed by the influence of electromagnetic forces and usually comprises two or more toroidal dominating recirculating vortices. Flow patterns obtained with 2-D solvers based on Reynolds averaged Navier–Stokes (RANS) equations usually are in good agreement with estimated and measured time-averaged flow velocity values. The resulting spatial distribution of the temperature and alloy compound concentration depends strongly on the heat and mass exchange between the vortices of mean flow. At the present time, different modeling techniques are being used to achieve agreement with the experiment.[1,2,3] Our numerical investigations show that two-equation turbulence models, e.g., k-e and others, fail to describe correctly the heat- and mass-transfer processes between the main vortices, when a standard parameters set is used. An engineering approach developed for this problem is described in Reference 4; however, it is necessary to investigate advanced simulation methods for more generic and therefore universal flexible solutions. Due to the permanent growth of accessible high powerful computational resources, nowadays, it is possible to run more complicated transient and three-dimensional (3-D) numerical calculations of fluid dynamic problems using advanced turbulent models with higher time and volume resolution requirements and to get reliable results in reasonable time. Concluding all these preconditions, the calculations presented in this article were devoted to application of the large eddy simulation (LES) method for turbulent recirculating flows, which often occur in various industrial proA. UMBRASHKO, Postdoctoral Candidate, E. BAAKE, Professor and Academic Director, and B. NACKE, Professor and Head of Department, are with the Institute for Electrothermal Processes, University of Hannover, D-30167 Hannover, Germany. Contact e-mail: [email protected] A. JAKOVICS, Associate Professor, is with the Faculty of Physics and Mathematics, University of Latvia, Riga, Latvia. Manuscript submitted November 30, 2004. METALLURGICAL AND MATERIALS TRANSACTIONS B
cesses where liquid metal is acting by electromagnetic forces. II.
EXPERIMENTAL RESULTS
The experimental measurements of the melt flow velocities are carried out in a laboratory induction crucible furnace (ICF), shown in Figure 1, where Wood’s metal (50 pct bismuth, 25 pct lead, 12.5 pct tin, and 12.5 pct cadmium) is used as the model melt. The main parameters of this model furnace are given in Table I. Twelve-turn
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