HFE-7100 Droplet Interaction with a Superheated Surface

The dynamics of HFE-7100 droplet interactions with a heated sapphire surface at superheat from 10 to 100°C for Weber numbers from 25 to 345 are considered. Top- and side-view visualizations are performed using a high-speed camera supplemented by a stereomicroscope. Top view images allow us to follow the transitions to different boiling regimes, as well as to observe bubble formation, bubble density, bubble clusters, bubble absence, and the transparency of the spreading droplet during levitation. While side view images show the rebound and levitation heights and angles. The rebound, the formation of a vapor layer, and the conditions under which the droplet levitates as the substrate temperature rises are studied. The formation of finger-like structures, which can then form secondary droplets, is observed for high We number values.