Migration dynamics for liquid/solid interface during levitation melting of metallic materials. (April 2020)

• Record Type: Journal Article
• Authors: Cai, X.; Wang, H.P.; Wei, B.
• Is Part Of: International journal of heat and mass transfer. Volume 151(2020)
• Publication Date: 2020-04
• Subjects: Containerless processing -- Heat transfer -- Phase transition -- Liquid metal -- Levitation; Heat -- Transmission -- Periodicals; Mass transfer -- Periodicals; Chaleur -- Transmission -- Périodiques; Transfert de masse -- Périodiques; Electronic journals; 621.4022
• DOI: 10.1016/j.ijheatmasstransfer.2020.119386
• Languages: English
• ISSNs: 0017-9310

Abstract

Highlights: Based on the apparent heat capacity method and the Carman–Kozeny relationship, the migration dynamics for liquid/solid interface are deeply explored under a series of representative levitation conditions. To quantitatively describe the temperature uniformity of levitated solid sample, a defined number related to sample properties D 2 ρ σ − 1 k − 1 was proposed. A reliable temperature control mode for bulk metallic materials was realized through optimized levitation structure. The correlation between the heat transfer behaviors and the various factors (sample properties, levitation position and coil structures) were analyzed by coupling electromagnetic, heat transfer and hydrodynamics fields. The migration details are validated by the related EML experiments through the 16 × 16 × 16 mm cubic Al sample, and the migration behavior in under extreme conditions were predicted by simulation. Abstract: The migration dynamics of liquid/solid interface for bulk metallic materials under the electromagnetic levitation (EML) condition were investigated by the combination of numerical simulation and related EML experiments. Based on the apparent heat capacity method and the Carman–Kozeny relationship, a thermo-electromagnetic-hydrodynamic model was established to explore the phase transition including the migration of liquid/solid interface, the evolution of melt flow and the temperature distribution. The details of migration process were quantitatively analyzed under different levitation conditions. The space and time evolutions of liquid/solid interface migration features were strongly correlated with the electromagnetic field in levitation space. In addition, the correlation between the heat transfer characteristics and the levitation conditions was explored by the levitated sample with a preset deformation shape. In heating process, the sample reached the lowest equilibrium temperature and the minimum melting rate when it was levitated in the middle of the levitation zone. A defined number related to sample properties D 2 ρ σ − 1 k − 1 was proposed to quantitatively describe the temperature difference of levitated solid sample. The migration details were validated by EML experiment that an oval molten pool formed near the lower sample surface firstly. Then, the liquid/solid interface gradually moved up to sample top. The migration behaviors under extreme conditions were predicted by simulation that molten pools formed simultaneously on the upper and lower surfaces when the sample was balanced near the levitation ceiling.