Liquid anti-contamination systems for hybrid laminar flow control aircraft—a review of the critical issues and important experimental results

Abstract

Contamination of the aircraft leading edges by insects and other airborne particles is a major operational concern for the implementation of hybrid laminar flow control (HLFC)-an active drag reduction technique, which has the potential to produce significant fuel savings for airliners. A review of the critical issues is provided, encompassing the transition mechanism, insect distributions and concepts for contamination mitigation. The use of liquid/foam-based systems has proved to be very successful, as is evident in the review of experimental work.

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

“…Physical and chemical modifications to the wing leading edge surface are passive methods that have been investigated and include elastic surfaces [75,84,85,135,136], coatings [49][50][51][52][53]57,104,[125][126][127]142], soluble films [15,145] and fluid covers [15,86,87,137]. Elastic surfaces discussed in Section 7.3 were found to work well with minimal traces of insect residue, but had durability concerns.…”

“…wetting) over the wing then insect residue would stick to the non-wetted wing surfaces. Fluid covers formed through a continuous liquid discharge from the deicing system were successful in preventing a majority of insect residue from adhering to the surface; however, it was only effective when turned on prior to insect impacts [15,86,87,137]. Besides ensuring that the fluid completely wets the surface, the system must be continuously operated during the portions of the flight profile where insects are a problem.…”

“…Besides ensuring that the fluid completely wets the surface, the system must be continuously operated during the portions of the flight profile where insects are a problem. A review of the use of liquid anti-contamination systems for HLFC is discussed in Young and Humphreys [137].…”

“…However, if the speed at which the insect impacts the surface is sufficient to cause the insects' cuticle to rupture, adhesion of the insect to the surface might still occur. The viability of this concept, however, has been questioned by certain authors [137] with others suggesting that it may still prove useful in conjunction with other protection concepts [54].…”

Engineered Surfaces for Mitigation of Insect Residue Adhesion

“…4 More recently, Young and Humphreys reviewed insect residue adhesion mitigation approaches that were flight tested. 5 The most promising mitigation strategies demonstrated on a Lockheed Jetstar aircraft flown under simulated airline service conditions were continuous liquid discharge and shielding via a Krueger-type leading edge device. 6,7 The continuous liquid discharge approach was effective when the system was on continuously to keep the wing surface completely wetted.…”