Date of Award

2013

Document Type

Thesis

First Advisor

Kizito, Dr. John P.

Abstract

Icing is widely recognized as one of the most dangerous, and potentially fatal, weather hazards in aircraft operations. Ice accretion on lifting surfaces is known to increase flow separation and drag, decrease lift, alter the moment and pitch of an aircraft, and cause undesired vibrations throughout the aircraft structure, all of which can lead to loss of control of an aircraft and accidents. It is for these reasons that developing methods to deter ice adhesion to aircraft structures is important to the aircraft operations. The average adhesive strength of ice on aluminum at -5, -10, -20, and -30C, was measured to be 0.2150.031, 0.1840.031, 0.2130.041, and 0.2020.035 MPa respectively, suggesting that temperature does not affect on the adhesive strength of ice. The adhesive strength of ice was then measured on bare and methoxymethylethoxypropanol, polymethylhydrosiloxane, and octylphenol ethoxylate treated aluminum, stainless steel, copper, and polycarbonate substrates at -10C. None of the surfactants used in the present study were found to be truly ice-phobic. Wettability was measured on the surfaces of all substrates used. The octylphenol ethoxylate, a surfactant that caused all of the materials observed in the present study to exhibit superhydrophilic surface properties, was revealed to be the only surfactant to reduce the adhesive strength of ice on all of the substrates. At -40C the volumetric freeze rate of a sessile droplet was measured to be 4.62 mm3/second, and the duration of the entire freezing process of a sessile droplet was 10.67 seconds. Icing is widely recognized as one of the most dangerous, and potentially fatal, weather hazards in aircraft operations. Ice accretion on lifting surfaces is known to increase flow separation and drag, decrease lift, alter the moment and pitch of an aircraft, and cause undesired vibrations throughout the aircraft structure, all of which can lead to loss of control of an aircraft and accidents. It is for these reasons that developing methods to deter ice adhesion to aircraft structures is important to the aircraft operations. The average adhesive strength of ice on aluminum at -5, -10, -20, and -30C, was measured to be 0.2150.031, 0.1840.031, 0.2130.041, and 0.2020.035 MPa respectively, suggesting that temperature does not affect on the adhesive strength of ice. The adhesive strength of ice was then measured on bare and methoxymethylethoxypropanol, polymethylhydrosiloxane, and octylphenol ethoxylate treated aluminum, stainless steel, copper, and polycarbonate substrates at -10C. None of the surfactants used in the present study were found to be truly ice-phobic. Wettability was measured on the surfaces of all substrates used. The octylphenol ethoxylate, a surfactant that caused all of the materials observed in the present study to exhibit superhydrophilic surface properties, was revealed to be the only surfactant to reduce the adhesive strength of ice on all of the substrates. At -40C the volumetric freeze rate of a sessile droplet was measured to be 4.62 mm3/second, and the duration of the entire freezing process of a sessile droplet was 10.67 seconds.

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