Time dependent 2D flow structure measurements arising from melt stirring by means of various AC magnetic fields

We present an experimental study concerning the flow inside an isothermal liquid metal column exposed to various magnetic field configurations. This paper is aimed at highly resolved, quantitative velocity measurements in the eutectic alloy GaInSn by means of the pulsed-wave ultrasound Doppler method. A novel ultrasound system was used to measure two-dimensional velocity fields of the secondary flow in the radial-meridional plane. The imaging system employs two arrays each of 25 transducer elements allowing for a fast electronic traversing with concurrently high spatial and temporal resolution. The study considers time-modulated fields or combinations of traveling magnetic fields (TMF) and rotating magnetic fields (RMF) revealing different flow structures and flow intensities. The results demonstrate different variants of electromagnetic melt stirring, some of them showing the potential to enhance the stirring efficiency and to optimize casting properties during solidification.