Constellation, le dépôt institutionnel de l'Université du Québec à Chicoutimi

Résumé

Residues of de-icing or anti-icing fluid, applied to aircraft on the ground, may produce, in some instances, lift loss at takeoff. The main objective of this work is to provide introductory information on the possible increase of lift loss in the case of supercooled droplets precipitation (freezing rain, drizzle, and fog) during taxi and ground acceleration. The study is performed on a 2D airfoil model set in the icing wind tunnel at the Universite du Quebec a Chicoutimi. The work concentrates on the lift measurement of a wing model subjected to wind acceleration and rotation, simulating those of a B737 aircraft. The fluids tested include three experimental anti-icing fluids. The supercooled precipitation is generated at a rate of 6.5 g/dm 2/hr with 33μ MVD droplets for contamination levels equivalent to 15% and 30% dilution of the fluid. The experimentations are performed at -10°C and -20°C. At low temperature, when exposure time is large enough to induce high fluid dilution (about 30%), the additional lift penalty may be enough to exceed the temporarily acceptable level of takeoff lift loss for large aircraft. This effect seems to correspond to the formation of a viscous mixture of fluid and ice that is similar to wet snow. Further work is recommended to confirm these findings for currently certified type I and type II fluids.