Use of Superhydrophobic Surfaces for Performance Enhancement of Aerial–Aquatic Vehicles

Abstract

Aerial–aquatic robotic vehicles show great potential in assisting in disaster response and environmental monitoring. However, to undertake these missions, they need to overcome the challenges of power requirements for takeoff and the difficulty of transitioning reliably between the air and water media. The use of superhydrophobic surfaces offers solutions to these challenges by reducing the wetted surface area of such robotic vehicles. In this article, a range of superhydrophobic surfaces is analyzed for wettability and robustness performance to ascertain their benefits as a design feature for drag reduction in aerial–aquatic robotic vehicles. The silicon dioxide nanoparticle spray coating show the most superhydrophobicity measuring a static water contact angle of 174.8°. The coating's robustness tests yield a similar performance to that of laser‐engraved brass with 200 μm groove separation, displaying a contact angle of 133.0° after ten finger strokes. The silicon dioxide nanoparticle spray is then used for drag reduction testing due to its ease of coating complex 3D geometries among the techniques explored in this study. The spray is applied to the hull of a sailing–flying robot, which resulted in the robot's drag reduction averaging 40% in the hydroplaning regime.

Keywords

• Cassie–Baxter state
• contact angle
• drag reduction
• droplet bounce
• robustness
• superhydrophobicity