An Experimental Study on the Durability of Icephobic Slippery Liquid-Infused Porous Surfaces (SLIPS) Pertinent to Aircraft Anti-/De-Icing

Abstract

Recently, bio-inspired surfaces have been found to be hydrophobic and/or icephobic, which has very low adhesion force for water and/or ice. When bio-inspired surfaces are applied for aircraft icing mitigation, they would suffer erosions due to high-speed impacting of the water droplets in the form of fog/mist. However, the knowledge of the coating durability regarding spray erosion is still quite limited. In the present study, an experimentally investigation was conducted to evaluate the durability of a PTFE membrane based slippery liquid infused porous surface (SLIPS) subject to water spray erosion, in comparison to that of a commonly used superhydrophobic surface (SHS) coating (i.e., a commercially-available Hydrobead® SHS coating). A wind driven spray generator was established with the spray erosion speed controllable from 45 m/s to 95 m/s. The anti-icing performance of the SHS and the SLIPS was validated in an icing research wind tunnel. Impact dynamics of individual water droplets at high Weber number about 3,000 and water spray erosion process of the SHS and the SLIPS were compared. The wettability-based coating lifetime was analyzed by measuring the dynamic contact angles on the SHS and the SLIPS under water spray erosions with different velocities. A cumulative-fatigue-damage theory was used to help predict the coating life time for in-flight aircraft icing mitigation. It turns out that the SLIPS could maintain its hydrophobicity better than the SHS under a moderate spray erosion speed. The mechanism of the spray erosion process for the SHS and the SLIPS was also examined in this study.