Ice Accretion and Icing Technology

Abstract

Ice adhesion on critical aircraft surfaces is a serious potential hazard that runs the risk of causing accidents. For this reason aircraft are equipped with active ice protection systems (AIPS). AIPS increase fuel consumption and add complexity to the aircraft systems. Reducing energy consumption of the AIPS or replacing the AIPS by a Passive Ice Protection System (PIPS), could significantly reduce aircraft fuel consumption. New coatings with superhydrophobic properties have been developed to reduce water adherence to surfaces. Superhydrophobic coatings can also reduce ice adhesion on surfaces and are used as icephobic coatings. The question is whether superhydrophobic or icephobic coatings would be able to reduce the cost associated with AIPS. To address this concern, this paper reviews the current knowledge on superhydrophobic and icephobic coatings, proposes a parameter to quantify the coating hydrophobicity level and presents methods to adapt available experimental data to aircraft applications. A second important question is whether the durability of superhydrophobic coatings is adequate for aircraft applications. Most of the available coatings that can reduce AIPS power consumption show poor erosion resistance and therefore have no practical use. To help coating manufacturers develop coatings adapted to aircraft applications, aircraft erosion test guidelines are presented. Experiments have demonstrated that superhydrophobic coatings can significantly reduce AIPS power consumption; the savings depend on the hydrophobicity level of the coating. However, erosion resistance is the biggest challenge for manufacturers and designers of coatings. Superhydrophobic and icephobic coatings need to be developed to satisfy erosion requirements. Ice phobic coatings performance needs to be improved as well.