Evaluation of commercially available materials to mitigate insect residue adhesion on wing leading edge surfaces

Surface contamination from insect strikes on aircraft wing leading edges can induce localized boundary layer transition from laminar to turbulent flow, resulting in increased aerodynamic drag and reduced fuel efficiency. As aviation fuel costs continue to climb, strategies to reduce fuel burn using laminar flow have led to renewed interest in surface modifications to minimize the effects of insect residue adhesion on aircraft wings. Under NASA's Environmentally Responsible Aviation Program, insect residue adhesion-resistant coatings are being studied as an approach for drag reduction. A series of aluminum alloy test surfaces were coated with commercially available materials and characterized using contact angle goniometry. The surfaces were subsequently subjected to controlled impact of crickets using a custom-built pneumatic insect delivery device. Impact events were recorded and analyzed using high-speed digital photography and characterized using optical surface profilometry. Residue adhesion was observed on all of the coatings investigated. The cricket impact event was related to liquid droplets impacting surfaces at high velocities and was analyzed as such. Coating surface energy was determined to influence residue adhesion.

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► Several potential insect adhesion mitigating coatings were evaluated.
► Insect hemolymph has surface tension properties similar to ethylene glycol.
► Cricket impact dynamics were relatable to liquid droplet behavior.
► Cricket residue radius correlated with ethylene glycol receding contact angle.