Preventing Atmospheric Icing in Aviation: Passive Repulsion of Super Cooled Water Droplets through Hydrophobic Nanocomposites

Abstract

The aviation industry already consists of a complex system of strict regulations related to operation and maintenance, where severe weather conditions further challenge flight operations. Recent research has shown that most aircraft accidents are caused by icing externally, where severe icing conditions lead to the critical degradation of the aerodynamic effectiveness – increasing the stall speed. If only a thin film of ice accumulates on the airframe, it will rapidly increase the risk for a fatal accident to occur.

The following thesis addresses critical icing conditions that might substantially affect the aerodynamic performance and propose an accessible method of a hydrophobic coating to mitigate the risk of ice accretion on planes.

The results show that the most exposed phase within in-flight icing occurs at cruising altitude, with glaze ice accretions. A risk assessment of components suggests that the wing part has the most significant effect on aerodynamic sustainability. A further CFD analysis of the wing section of an Airbus A320neo, at cruising altitude, was simulated and compared with and without glaze ice conditions. The ice formation led to a mass of 2.3 kg after 100 seconds, while measurements determined that the drag capacity was increased significantly. The lifting capacity was virtually unaffected.

Furthermore, a feasibility study has been conducted with the underlying goal of identifying the most promising of anti-icing coatings for aircraft. To date, there are no coat-ings capable of independently functioning as a passive anti-icing system. However, findings reveal two promising methods that were further carried out for testing.

The preparation of a highly hydrophobic and ice phobic coating based on Zinc Stearate (ZnSt) and a curable Polydimethylsiloxane (PDMS) was carried out. Indicatively, the coating showed high water repellent and ice repellent properties by measuring the ice adhesion, which reduced the interaction between the aluminum surface and freezing water droplets by over 50%.