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Technical Paper

Aerodynamic Flow-off of Type II and Type IV Aircraft Ground Anti-icing Fluids

2003-06-16
2003-01-2106
The certification process for aircraft ground anti-icing fluids involves flat plate wind tunnel aerodynamic flow-off tests. This test method was developed in 1990 from flight and wind tunnel tests results on full scale and model airfoils, and flat plates; the resulting lift losses were then correlated to the Boundary Layer Displacement Thickness (BLDT) on a flat plate. This correlation was made for Type II fluids existing at the time. Since the introduction of Type IV fluids in 1994, with significantly longer anti-icing endurance times, the same test procedure was applied. However, Type IV fluids are generally more viscous than Type II fluids of the same concentration. At the FAA's request, a study was undertaken to see if aerodynamic certification testing should be different for Type IV fluids as opposed to Type II.
Technical Paper

Simulation of Freezing and Frozen Precipitation for the Evaluation of De/anti-icing Systems

2007-09-24
2007-01-3318
Simulating freezing and frozen precipitation in an indoor laboratory setting can permit year round evaluation of de/anti-icing systems and fluids. At AMIL, freezing rain, freezing drizzle, icing fog and in-cloud icing as well as frost, snow, ice pellets and icing clouds can be simulated in a variety of cold chambers of different heights and with different wind conditions using specialized spraying systems and temperature set-ups. Freezing rain is simulated using a 9 m high vertical chamber capable of supercooling water droplets from 100 to 1000 μm, so they freeze not long after impact. The freezing drizzle is simulated in a 4 m high chamber where supercooled droplets from 50 to 250 μm freeze on impact. Icing fog and in-cloud icing are simulated with the help of a pneumatic spray nozzle system which allows for a finer water spray, in the 20 μm diameter range. The frost is simulated by saturating a cold room with humidity generated from a heated, temperature controlled water bath.
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