Center Icing Research Research Articles

Aerodynamic effects of aircraft ground deicing/anti-icing fluids

This article presents the results of flight and wind-tunnel investigations of the aerodynamic effects of aircraft ground deicing/anti-icing fluids on a Boeing 737-200ADV. The flight tests were performed in Kuopio, Finland, and the wind-tunnel tests were performed at the NASA Lewis Research Center Icing Research Wind Tunnel (IRT). Both types of commonly used fluids, those characterized by Newtonian and nonNewtonian viscosity behavior, were evaluated. Results of the tests indicate that the fluids remain on aircraft surfaces until well after liftoff and may cause measurable lift loss and drag increase, depending on the temperature, dilution, and specific characteristics of each fluid. A secondary wave of fluid which occurred at takeoff rotation was observed. Capillary wave action within the secondary wave is considered to be the source of the fluid's adverse aerodynamic effects at high angles of attack. Wind-tunnel testing and computational fluid dynamics analysis indicate that the fluid effects are airplane configuration dependent. This article also describes how results from these tests, other data, and airplane performance analyses were used to define an aerodynamic acceptance test for the fluids.

Water droplet impingement on airfoils and aircraft engine inlets foricing analysis

This paper includes the results of a significant research program for verification of computer trajectory codes used in aircraft icing analysis. Experimental water droplet impingement data have been obtained in the NASA Lewis Research Center Icing Research Tunnel for a wide range of aircraft geometries and test conditions. The body whose impingement characteristics are required is covered at strategic locations by thin strips of moisture absorbing (blotter) paper and then exposed to an airstream containing a dyed-water spray cloud. Water droplet impingement data are extracted from the dyed blotter strips by measuring the optical reflectance of the dye deposit on the strips with an automated reflectometer. Impingement characteristics for all test geometries have also been calculated using two recently developed trajectory computer codes. Good agreement is obtained with experimental data. The experimental and analytical data show that maximum impingement efficiency and impingement limits increase with mean volumetric diameter for all geometries tested. For all inlet geometries tested, as the inlet mass flow is reduced, the maximum impingement efficiency is reduced and the location of the maximum impingement shifts toward the inlet inner cowl.