Thermal atomization on superhydrophobic surfaces of varying temperature jump length

This paper presents an experimental study of drop impingement , thermal atomization on hydrophobic and superhydrophobic (SH) surfaces. Superhydrophobic surfaces having both microscale and nanoscale geometry are considered. Microscale SH surfaces are coated with a hydrophobic coating and exhibit micropillars and cavities which are classified using the surface solid fraction and center to center pitch. The solid fraction and pitch values explored in this study range from 0.05-1.0 and 8-60 & mu;m respectively. Nanoscale textured surfaces are created by applying a blanket layer of carbon nanotubes. Both types of surfaces are further classified by a temperature jump length (AT). All experiments were conducted at We = 85. Results of atomization as a function of time for the impingement event are provided for several surfaces of varying surface geometry, surface temperature , temperature jump length. Nanoscale SH surfaces are shown to completely suppress atomization at all conditions explored. Results of the maximum atomization that occurred on a given surface are also shown as a function of the surface temperature. The surface temperature at which the maximum atomization occurs varies with surface geometry. Further, the time after impact when the maximum atomization occurs is also a function of the SH surface parameters. In general, the maximum atomization magnitude and the surface temperature at which maximum atomization occurs each decrease with increasing AT. Further, the time when maximum atomization occurs increases with increasing AT.