Behavior of Sliding Angle as Function of Temperature Difference between Droplet and Superhydrophobic Coating for Aircraft Ice Protection Systems

Abstract

A hybrid anti-/de-icing system combining a superhydrophobic coating and an electrothermal heater is an area of active research for aircraft icing prevention. The heater increases the temperature of the interaction surface between impinging droplets and an aircraft surface. One scientific question that has not been studied in great detail is whether the temperatures of the droplet and the surface or the temperature difference between the two dominate the anti-/de-icing performance. Herein, this scientific question is experimentally studied based on the mobility of a water droplet over a superhydrophobic coating. The mobility is characterized by the sliding angle between the droplet and the coating surface. It was found that the temperature difference between the droplet and the coating surface has a higher impact on the sliding angle than their individual temperatures.

An Experimental Investigation of Evaporation of Ethanol–Water Droplets Laden with Alumina Nanoparticles on a Critically Inclined Heated Substrate

“…This could be attributed to an increase in the adhesion force between the droplet and the substrate as its temperature increases. 62 The component of gravity parallel to the inclined surface propels the droplet, and thus, as gravity overcomes the adhesive force, it starts to migrate downward. Second, the critical angle increases as the ethanol concentration decreases because ethanol has a lower surface tension than water.…”

“…First, the critical angle of inclination is generally observed to increase with an increase in the substrate temperature. This could be attributed to an increase in the adhesion force between the droplet and the substrate as its temperature increases . The component of gravity parallel to the inclined surface propels the droplet, and thus, as gravity overcomes the adhesive force, it starts to migrate downward.…”

Super‐liquid‐repellent thin film materials for low temperature latent heat thermal energy storage: A comprehensive review of materials for dip‐coating

“…STFs could promote the shedding of PCM-solid-layers from HX surfaces in LHTES and modify the phase change process during heat discharge, thereby enhancing heat delivery efficiency. Although they find extensive application in many fields (ie, drag reduction, 24 industrial boiling and condensation, 25 antifouling, 26,27 de-icing [28][29][30][31][32][33] and defrosting, [34][35][36] etc. ), their contextual application in LHTES systems for recovery, storage and transportation of low temperature process heat (up to $250 C) is novel.…”

Fundamentals and utilization of solid/ liquid phase boundary interactions on functional surfaces

“…Another common quantification value of wetting is the sliding angle (s.a.) [24], which is the angle for a macroscopically plain surface to be tilted at to make the contacting liquid moving downwards by its own weight (Fig. 1 c)).…”