Aerodynamic acceptance test for commuter aircraft de-icing and anti-icing fluids

Abstract

The clean aircraft wing surface requirement, at the time of take-off, has led to a definition of aerodynamic acceptance for anti-icing fluids applied on aircraft on the ground. For large aircraft, an AMS/ISO standard testing procedure has been designed and implemented to demonstrate the negligible aerodynamic effect of the residues of a candidate fluid : the Flat Plate Elimination Test. This work describes the modified procedure which enables standard evaluation of anti-icing fluids for commuter aircraft and an assessment of experimental anti-icing fluids for commuter aircraft (Type III fluids). The testing method, similar to that for large aircraft, determines the boundary layer displacement thickness (BLDT) induced by a film of anti-icing fluid, applied on a flat horizontal plate and subjected to a linear acceleration of 2.1 m/s, during 16.5 s, up to 35 m/s. The method is shown to be repeatable and accurate. Flat plate results are shown to correlate well with a 2D model study performed at NASA Lewis Research Center by Boeing Canada de-Havilland Division. According to this correlation, the maximum acceptable BLDT value, for aircraft with a rotation velocity between 60 KT and 100 KT, was found to be 10.6 mm. One experimental fluid was found to be acceptable down to about -25°C. Other fluids are also acceptable in a limited temperature range. No Type II fluid, in this study, was found acceptable for commuter aircraft. f Professor, Research Associate, Ph. D. Student, members AIAA Copyright © 1998 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved. Nomenclature a wind acceleration (m/s) te time of elimination measurement(s) tfo fluid initial thickness (m) tm time at the end of acceleration (s) tr time of rotation (s) Clmax 2D equivalent of aircraft CLmax (-) ACi/Ci 2D lift loss (%) Vr rotation velocity (m/s or KT) Vm maximum velocity (m/s or KT) Ta air temperature (°C) Tf fluid temperature (°C) T2 air temperature at section 2 (°C) TS air temperature at section 3 (°C) a angle of attack (°) a rotation rate (°/s) 5ave* average BLDT (m) BLDT with no fluid (m) BLDT over fluid (m) maximum acceptable BLDT (m) BLDT with reference fluid (m) Sf*