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

Résumé

Since 1987, de-icing procedures for aircraft on the ground have been increasingly modified to account for longer queuing time before take-off. New fluids that exhibit long-lasting ice protection have been introduced. These anti-icing fluids are non-Newtonian (pseudo-plastic) in order to be highly viscous when the aircraft is at rest while losing viscosity during acceleration before take-off rotation. The objective of the present work is to implement an improved standard testing procedure recommended by the Aerospace Industries Association (AIA) and the Association Europeenne des Constructeurs de Materiel Aerospatial (AECMA) that defines aerodynamic acceptance of de-icing/anti-icing fluids for large aircraft. The experimental set-up consists of a rectangular duct, 1.5 m long, with a 30 cm by 10 cm cross-section, which is fitted in a cold recirculated wind tunnel and instrumented to measure temperatures and boundary layer displacement thickness (BLDT) during a wind acceleration that simulates ground acceleration of a type B-737 aircraft. Previous work (Carbonaro, 1985-87) demonstrated that the BLDT was well-correlated to the lift loss induced by the fluid remaining on the wing at take-off. Consequently, the BLDT that is produced by accelerating air over a 2 mm fluid layer on the bottom of the test duct can be used to identify acceptable levels of lift reduction for a given fluid. A reference fluid is used to present and validate the overall procedure, and five leading commercial fluids that exhibit acceptable behaviour above -20°C are evaluated.