Laboratory testing of insect contamination with application to laminar flow technologies, Part I: Variables affecting insect impact dynamics

Critical considerations in the mitigation of insect residue contamination on aircraft surfaces – A review

“…The orientation of the insect upon impact also influences the amount of residue obtained, which in turn affects the measured residue area and height values, subsequently influencing the apparent performance of the candidate coatings. Kok et al [57] showed that a threshold velocity exists, when the orientation of the insect no longer has an effect on the resulting rupture pattern -this was found to be approximately 55 72.7 m/s. The effect of body orientation on the rupture velocity could explain why a large scatter in results was found in data obtained by Coleman [48].…”

“…It was found that the Krueger shield was effective in preventing insect residue accumulation on the upper surfaces of the airfoil when deployed in an optimum high lift configuration. Kok et al [57] examined the effect of impact angle and speed on the excrescence height and area. It was found that if the impact angle was kept constant and the speed variable, the rupture patterns obtained at low speeds were significantly different than those obtained at higher speeds.…”

“…Kok et al [57] hypothesised that four distinct regimes exist during an insect impact, namely (1) sticking, (2) bouncing, (3) spreading and (4) splashing. Sticking of the insect body to the surface occurs if the insect impacts the surface with a low incoming velocity, sufficient to fracture its exoskeleton and release haemolymph, adhering the insect body to the surface.…”

“…Tests conducted by Tegarden [121] using houseflies, showed that a minimum velocity of 30.48 m/s was required for significant splattering of the insects and in order to obtain meaningful data, a majority of the tests were conducted at the maximum tunnel velocity of 91.44 m/s. A comprehensive study conducted by Kok et al [57] determined that several factors influence the rupture velocity of a single insect type -these include the gender and mass of the insect and the insect body orientation upon impact. It was found that if the insect impacts the surface wings first, the exoskeleton (which is densest in the area where the wings meet the body) offers significant protection against rupture, corresponding to a rupture velocity of 3071.9 m/s (tests were conducted at normal impact angles).…”

“…Kok et al [55] conducted tests on a flat plate in a laboratory scale wind tunnel using different insect species of the genus Drosophila (i.e. fruit flies) to determine the variance in the measured residue area and height values.…”