Evaluating aerodynamic viscous drag reduction performance of superhydrophobic coatings

Applying different types of coatings to various surfaces, such as airfoils, has shown a significant improvement in drag reduction. Among these coatings, superhydrophobic (SHP) coatings, while primarily used for anti-icing, have shown evidence of drag reduction as well. However, with the development of different SHP compounds, unique surface characteristics, durability in external environments, and consideration of the large-scale applications such as wind turbines, there is more to be understood about SHP coatings. This study explores the effect of a specialized SHP coating on the surface characteristics and the viscous drag force on a smooth flat plate for a range of Reynolds numbers. A flat plate was coated with SHP coatings using a high-volume, low-pressure (HVLP) spray applicator and were cured using the recommended conditions for 24 to 48 hours. Data were acquired using an in-house developed elastomeric force balance (EFB) and Oil Film Interferometery (OFI). Drag reduction efficiency of the various coatings will be discussed.