Siltuma un vielas pārneses procesi elektromagnētiski ierosinātās recirkulatīvās plūsmās

Abstract

This work is devoted to the problem of heat and mass transfer processes in the turbulent recirculated liquid metals ows driven by the electromagnetic forces. This kind of ows often takes place in various practical applications like melting of metals and alloys. Experimental investigations using physical model of induction furnace have shown that the ows are unstable and large amplitude low-frequency oscillations were revealed by velocity measurements. However, the existing turbulence modeling approaches were not able to calculate correct temperature distribution for mentioned ow types. Extended numerical and experimental studies have been performed for three dierent types of induction furnaces, where the velocity proles and temperature elds were examined. The modelling results of the crucible induction furnace have shown the necessity for the adequate simulation of the low-frequency oscillations observed in the experiment, while the model of the induction crucible furnace gave the possibility to study thoroughly the characteristics of these ow instabilities. The new modelinfg approach based on Large Eddy Simulation technique has been applied in order to capture this phenomenon numerically, since traditional two-equation turbulence models do not provide necessary opportunities. The measurements and numerical calculations of the model induction crucible furnace, which were focused on the specic parameters of the low-frequency oscillations, gave the possibility to improve the proposed modeling method and also to determine its application possibilieties. The LES technique has been further applied for the modelling of the Aluminium and Titan-Aluminium melting process in the induction furnace with the cold crucible. The corresponding temperature and velocity measurements have been done in Aluminium melt. The fully three-dimensional electromagnetic analysis of the installation has been used as a base for the transient three-dimensional coupled hydrodynamic and thermal calculations. The parameter study has been performed in order to derive the tendencies for possible optimization of the melting process in induction furnace with cold crucible.