Could Superhydrophobic Surfaces be a Realistic Solution for Running-Wet Areas?

Abstract

<div class="section abstract"><div class="htmlview paragraph">Thermal ice protection systems (IPS) are used extensively in aeronautics. They are tailored according to the aircraft characteristics or flight envelope and can be used in different modes, anti-icing to avoid ice accretion or de-icing to remove the ice once accreted. A relevant issue by this application is the runback icing, caused by the downstream flow of melted or running water to unprotected areas, where activation is not possible in terms of energy consumption. Passive systems are being explored to complement or replace active systems, although, up to now, solutions have not been reported with the required performance for real-life applications.</div><div class="htmlview paragraph">One of the most commonly reported anti-icing strategy relays on superhydrophobicity, i.e., it is based on the water roll-off capacity of Cassie-Baxter superhydrophobic surfaces (CB-SHP). Precisely, running wet phenomena, where liquid water is flowing on the surface, could be an appropiate application field for this type of materials. Herein, we have explored the behavior and limitations of a stable, newly developed, CB-SHP material to protect a runback section under icing conditions (temperature, air speed, liquid water content, droplet size distribution, and angle of attack) closer to those encountered in a wing airfoil.Two icing mechanisms, running-wet and direct impingement of supercooled microdroplets, have been evaluated for short (2 minutes) and long (10 minutes) period tests. It is found that the tested SHP material improved the performance of reference polyurethane (PU) paints, avoiding any ice accretion at low air speeds and low angles of attack.</div></div>