Laboratory investigation into anti-contamination coatings for mitigating insect contamination with application to laminar flow technologies

Abstract

Insect contamination on aircraft leading edge surfaces can result in premature transition of the boundary layer, leading to an increase in skin friction drag and fuel consumption. An evaluation of candidate anti-contamination coatings was undertaken. Coatings were characterized before impact testing. Surface energy was quantified by dynamic contact angle analysis and surface roughness measured using a profilometer. Superhydrophobic coatings showed a reduction in contamination when compared to the higher surface energy specimens tested. The surface topography and chemistry, in particular the sliding angle of a coating, were found to have a significant influence on the effectiveness of a coating. Insect residue areas were theoretically predicted using high-speed liquid droplet theory and compared to experimentally obtained results. Tests with different insect species were conducted to investigate the effect of insect size and type on the effectiveness of the coatings and the evaluation procedure. Good correlations were obtained between the two test facilities used. The effect of substrate temperature on insect impact dynamics and adhesion was also evaluated.