Aerodynamic effect of icing/rain impacts on super-hydrophobic surfaces

The rain impact and ice accretion on different aerodynamic constructions represent a large problem to their safety and operation. Most current de-icing systems include either physical or chemical removal of ice, which is resource- and energy-intensive as well as environmentally polluting. A more desirable approach to prevent initial ice formation from water droplets on a surface is to employ highly ordered super-hydrophobic materials, which mimic lotus leaves and other natural dirt- and water-repelling surfaces and reproduced in many laboratory tests.

The ability to fend off water droplets could lead to prevention of icing as an inherent material property, which further would prevent ice formations, rather than fighting its build-up. Our objective is to draw attention to problems of an extension of this effect to technical applications. The main idea of the icing or rain protection of the different aerodynamic constructions may be the use of super-hydrophobic thermoplastic polymers with the water-repellent properties to prevent corrosion, improve aerodynamics or add self-cleaning properties to the material.

The purpose of the present study is to explore the possibility of using a fast and cheap technology of R2R-EC to enable the fabrication of nanostructures on polymer foils of sizes ranging from 50 nanometers and up to 100 micrometers with the aim of improving the ice-cleaning and water-repellent properties of the coating.

This high-speed and low-cost lithography method is developed at DTU and Danapak Flexibles A/S. These super-hydrophobic surfaces with water-repelling structures provide rebound actions on the impacting droplets with the large contact angle θ. For the foils with the different micro- and nanostructures, the wetting properties are measured and impact with single droplet is presented.

These coatings can be used for different engineering tasks, which need to establish and test new anti-icing/rain solutions for complex aerodynamic flows. We will start the present investigation from the initial point to include main aspects of the previous water-repellent investigations and test a single droplet impacts on the surface with the thermoplastic foil for the coating.