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

Mitsugu Hasegawa,Katsuaki Morita,Haruka Endo,Shigeo Kimura,Hirotaka Sakaue

doi:10.3390/aerospace8080219

Mitsugu Hasegawa, Katsuaki Morita + Show 3 more

Open Access

https://doi.org/10.3390/aerospace8080219

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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.

Highlights

Aircraft icing is a hazardous event for many aircrafts, because it impacts aerodynamic performance leading to potentially fatal accidents [1,2,3,4,5]
The increasing sliding angle can be caused by the condensation of water vapor due to the temperature difference between the droplet and the superhydrophobic coating surface
The temperature difference was given by setting the temperatures of a droplet and a superhydrophobic coating surface to −5 ◦C, 5 ◦C, and 25 ◦C

Summary

Introduction

Aircraft icing is a hazardous event for many aircrafts, because it impacts aerodynamic performance leading to potentially fatal accidents [1,2,3,4,5]. A hybrid anti-/de-icing system combining a superhydrophobic coating with an electrothermal heater has recently been proposed to reduce energy consumption [10,11,12,13]. Ice accretion over the leading edge of a wing is melted by the heater. The melted water droplets can be removed from the superhydrophobic coating surface by gravity or an aerodynamic force, because the droplet’s mobility over the surface is enhanced by the hydrophobicity of the coating [14,15,16,17,18,19,20,21,22]. To enable a hybrid anti-/de-icing system, the superhydrophobic coating surface must promote this ease of droplet removal for different temperature conditions

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