Droplet impact on hot surfaces is widely encountered in industry and
engineering applications. In the present paper we investigate the effect of
the combination of the droplet liquid type and the solid surface type and
their effect on droplet impact dynamics. We test three surfaces, copper 110,
aluminum 1199 and stainless steel 304, and two liquids, water and ethanol.
These surfaces and liquids are characterized by high and low thermophysical
properties. The three surfaces are tested with water to investigate the
effect of the surface on the droplet dynamics. After that, we test both
liquids with aluminum. Our findings showed that the Leidenfrost temperature
does not always correlate with the surface thermal properties as reported in
the literature. Some surfaces can undergo changes because of the heating and
this reduces their initial thermal properties. For this reason, such
surfaces are capable to show two Leidenfrost temperatures because of the
thermophysical properties reduction during heating. Our findings also
revealed that the Leidenfrost temperature of liquids with low thermophysical
properties including surface tension, evaporation latent heat and density
show trivial effect by the droplet impact velocity; i.e. the Leidenfrost
temperature show trivial increase by increasing the droplet impact velocity.
Liquids with high thermophysical properties show significant Leidenfrost
temperature increase by increasing the impacting velocity.
Experimental Study of the Phenomenon of Droplet Impact upon a Liquid Surface