On the Influences of Adjacent Conducting Media and Coil Frequency on the Electromagnetic Field and Flow Characteristics in Solidifying Melts

摘要

This paper examines the electromagnetic and flow field modification caused by the placement of electrically conducting media in the vicinity of the coil and molten metal and the corresponding influences of coil operating frequency. The electromagnetic field characteristics were numerically calculated using the mutual inductance technique. An improved dual-zone model was employed to describe flow behavior in the mushy region, and accounts for flow damping via interactions between the crystallites and the turbulent eddies. Calculations were performed for unidirectional solidification of an Al-4.5 wt% Cu alloy in a bottom-chill mold undergoing EM stirring. It was found that the presence of shields greatly modified the Lorentz force distribution within the melt. This led to noteworthy changes in the flow directionality, as well as changes in the spatial variation of temperature as solidification progressed. It was also found that these effects were most pronounced at low frequencies. The significance of these findings with respect to solidification process design will be discussed.