Superhydrophobic coatings as a new strategy for energy saving anti/de-icing systems

The application of superhydrophobic coatings for the development and optimizations of anti/de-icing systems for aeronautics or wind turbines appears to be a promising strategy to combat icing. Whereas majority of studies dealing with coating has focused mainly on reducing ice adhesion forces, to more easily remove ice once it is formed, in this study we focus on promoting the shedding of liquid water as a way to reduce the total amount of water present on the surface, before it can freeze. The shedding of liquid water is promoted by reduction of airfoil surface wettability, which is measured by contact angle and contact angle hysteresis of a drop in contact with the surface. In our previous study [1] we already proofed that a coating strategy, used in combination with an anti-icing system, allows to significantly reduce heating power required to avoid ice formation in the collection zone and to reduce ice accretion. In the present work, we focus on two new aspects: first, the assessment of coating strategy performance when the heating system operates intermittently, as a de-icing system; second, the optimization of heating power distribution on the wing, for reducing heating power requirements. Tests were performed in a small icing wind tunnel (IWT) facility (air velocity of 28 m/s, air static temperature of -17°C, and mean volumetric diameter range 50-750μm). A segment of a NACA0021 airfoil that had electrical heating at its leading edge was used. The test article as described allows for installation of interchangeable segments in its midsection. Three different insertion segments with variable wettability, from hydrophilic to superhydrophobic, were used. Results show that a coating strategy is effective also when used in combination with a de-icing system, as it is effective with an anti-icing system.