Dynamics and temperature of droplets impacting onto a heated wall

This paper presents results of an experimental investigation of water droplet impacts onto a smooth heated plate made of nickel. A high-speed camera is used to observe the impact regimes (rebound, splashing, and deposition of a liquid film) for a large set of impact conditions (wall temperature, droplet incidence angle, velocity and size). The observations help specifying the conditions of existence of the regimes. In a second part of the paper, the emphasis is placed on the droplet heating during an interaction with the heated wall. The droplet temperature is measured with the help of the two-colour laser-induced fluorescence thermometry in the case of the different impact regimes. The droplet change in temperature during an impact is found to be dependent on the normal velocity but not on the wall temperature when it exceeds the Leidenfrost temperature. (C) 2008 Elsevier Ltd. All rights reserved