A videographic and numerical study of nonisothermal oscillation process for electrostatically levitated liquid Nb–Si alloy

The heat transfer and oscillation dynamics of the liquid Nb-17.3 at.% Si eutectic alloy at high temperatures of approximately 2200 K were explored with electrostatic levitation (ESL) technique. Different second-order oscillation modes of levitated alloy droplets were successfully induced by both excited oscillation with smaller amplitude and spontaneous oscillation with larger amplitude. Importantly, an oscillation mode transition from second to third order was observed as the alloy droplet size increased to 3.96 mm. Meanwhile, a mathematical model coupling heat transfer and droplet oscillation was developed to simulate this nonisothermal oscillation process. The entire thermal history was numerically predicted and proved consistent with experimental measurements. The shape evolution dynamics of second- and third-order oscillations together with the corresponding liquid flow patterns inside alloy droplet was revealed in detail, which helped to clarify the mutual influence mechanism between heat transfer and droplet oscillation.