The physics of insect impact and residue expansion

Abstract

The phenomena of insect impacts on aircraft surfaces are complex; therefore, tailoring surface properties to minimize the adhesion of insect residues is particularly challenging. By using a first-level approximation model, where an insect impact can be approximated as a water droplet impact, information can be leveraged toward understanding insect residue accretion. However, an insect consists of an exoskeleton covering hemolymph, which is significantly more complex than water. Therefore, the energetic requirement for exoskeleton rupture will be briefly considered and the properties of the hemolymph will be discussed. Next, relevant phenomena from water droplet impact studies will be used to describe events that occur during an insect impact. A more detailed analysis of the particular water droplet impact phenomena needed to describe and model insect impact events will be reviewed. Based on this analysis, several conclusions can be drawn regarding the surface properties most likely to be beneficial for the prevention of insect residue adhesion. Among these are the requirements for moderate hydrophobicity and surface roughness, as well as recognition that the prevention of insect residue adhesion can be approached by targeting specific phases of the event itself.