Performance study of ground deicing and anti-icing fluids
Aircraft ground deicing and anti-icing fluids are used to remove and prevent the accumulation of ice and snow on an aircraft while the aircraft is on the ground and are a key component in safe winter takeoff operations. While the fluids prevent the lift losses created by ice and snow formations, the fluids themselves are capable of generating lift losses beyond normal safety margins due to waves forming on the fluid's surface. Consequently for a fluid to be used on an aircraft, the performance losses created by the fluid must be shown to be within acceptable safety margins. This usually requires full scale takeoff testing of the aircraft with the fluid applied to the aircraft. Due to the difficulty, expense, and risk associated with such testing, aircraft manufacturers desire simulation techniques that eliminates or reduces the required full scale takeoff testing. This thesis developed a wind tunnel testing technique suitable for aircraft manufacturer's to assess the aerodynamic effects of a deicing or anti-icing fluid on their aircraft. The use of a wind tunnel allows for control of the test conditions and accurate measurement of a fluid's aerodynamic effects. To develop the testing technique, an extensive literature review was conducted with the aerodynamic effects and behaviors of deicing and anti-icing fluids identified and studied. Properties of existing deicing and anti-icing fluids were studied using both published data and experimental measurements made during this thesis. The fluid properties of deicing and anti-icing fluids affecting a fluid's aerodynamic performance effects on a wing were studied with viscosity being identified as the primary property affecting a fluid's lift loss. Minor to negligible lift loss dependencies were observed with surface tension and fluid density. As a proof of concept of the testing technique and to gain insight into the behavior of a fluid layer during takeoff, a wind tunnel model was designed and tested in the Wichita State University's Walter H. Beech subsonic wind tunnel. Simulated takeoff testing was conducted with a high viscosity pseudoplastic fluid with fluid properties similar to Type IV anti-icing fluids. Fluid effects on lift, drag, and pitching moment were studied along with boundary layer profiles, fluid depths, and surface wave speeds. The testing technique proved capable of measuring fluid effects in all of these variables with fluid behavior conforming to expected behaviors. The ability of various solid roughness types in mimicking a fluid's force and moment effects were studied with sandpaper roughness proving to be the most capable.