Experimental evaluation of flat plate boundary layer growth over an anti-icing fluid film

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

Introductory analysis of draining and freezing of de-icing fluids

The fluids used for de-icing and anti-icing procedures for aircraft on the ground are evaluated by standard performance tests conducted in a cold chamber. The “water spray endurance test” (WSET) is a laboratory simulation of the supercooled precipitation case which permits the identification of the period of protection provided, by a given fluid, against ice formation. The present work uses a simple mathematical model representing the WSET situation in order to provide analytical support to the variation of the protection time versus precipitation intensity. The numerical simulation does not account for all significant factors but is consistent with the general experimental behaviour and confirms the power law relationships between protection time and precipitation intensity

Introductory analysis of boundary-layer development on de/anti-icing fluid

When aircraft are kept on the ground for a significant period of time under cold precipitation, anti-icing fluids are used to prevent ice buildup. Unfortunately, at the time of takeoff, the residual fluid on wings modifies the boundary layer of the air and causes lift loss. The purpose of this work was to study the boundary-layer development of the air flowing above a horizontal flat plate covered with a de/anti-icing fluid film. The objective was to find the relationship between the air boundary layer and the geometric and dynamic characteristics of the air/fluid interface. This work consists of numerical and experimental studies. The experimental work contains a rheological study of the fluid and wind-tunnel tests on flat plates in order to describe the movement of the fluid during airflow acceleration. The numerical modeling is used for the prediction of the wave characteristics at the interface and for the determination of the integral relationships for rough boundary-layer conditions. The model of stability gave a good correlation between theory and experiment for the waveform at the air/fluid interface. A simple integral model determines an equivalent flat plate roughness that produces the same boundary layer as with the fluid. This equivalent roughness corresponds, in general, to the waveform, which indicates that the influence of the fluid seems to be only geometrical in nature

Laboratory evaluation of aircraft ground de/antiicing products

An icing laboratory facility has been set up at Université du Québec à Chicoutimi to evaluate the ice holdover times and the aerodynamic performances of commercial ground de/antiicing products. Ice holdover and aerodynamic performances of deicing and antiicing fluids are established through three standard laboratory tests: the Water Spray and High Humidity Endurance Tests, carried out m a climate chamber, and the Flat Plate Elimination Test, conducted in a cold wind tunnel. UQAC facility qualities for certification of commercial products under these AMS and AEA standard tests. This paper aims to describe the testing procedures recently implemented at UQAC icing laboratory for de/antiicing fluid evaluation and other research activities in this area

for Commuter Aircraft

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