Heat transfer from solid surfaces to impacting liquid droplets plays an important role in many industrial technologies such as power electronics cooling, spray cooling, engine performance, and pollutant emissions. hen a liquid droplet impacts on a surface heated above the liquid's boiling point, the droplet either immediately boils when it contacts the surfaces (contact boiling), or without any surface contact forms a Leidenfrost vapor layer towards the hot surface and bounces back (film boiling). We study the dynamics of the thin vapor layer (around 100 nm) between an impacting droplet and the superheated surface, and investigate how the boiling dynamics of the droplet change with impact inertia and substrate properties. We find that the whole impact dynamics is largely determined by the dimple and neck formation beneath the droplet at the very beginning of the impacting process.

 

报告人: 孙超 清华大学燃烧能源中心和热能工程系教授