Investigation of surface effects on ice formation

• Main Author: Achmad Mutamaqin Mohamed Ridzwan
• Other Authors: Chan Weng Kong
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Mechanical engineering::Fluid mechanics; Engineering::Aeronautical engineering::Aircraft; Engineering::Aeronautical engineering::Accidents and air safety
• Online Access: https://hdl.handle.net/10356/150549
• Institution: Nanyang Technological University

Ice formation on aircraft surfaces have proven to cause devastating effects. Current methods employed to curb this problem have been effective but only to a certain extent. In recent times, to fully prevent further accidents due to ice formation to occur, much research has been done on the hydrophobicity effect and how it can be applied on the surfaces of aircrafts. One of the most effective methods in fabricating hydrophobic surfaces is through chemical etching. In this study, 6061 Aluminum Alloy plates were used for the fabrication of hydrophobic surfaces to simulate an aircraft surface as close as possible. They were chemically etched using hydrochloric acid (HCL) as the etchant and the passivation process was carried out using ethanoic stearic acid. Research has shown that etching duration and etchant concentration were the key variants to achieve different hydrophobicity effects. Hence, in order to achieve an ideal hydrophobic surface, there exists an optimal combination of etching duration and etchant concentration to be used. On top of that, to measure the hydrophobicity of these test plates, the contact angle of water was measured. Eventually, the test plate that was etched using 4M HCL for 6 minutes was deemed to be the ideal hydrophobic surface as it produced the largest average contact angle of water of 155.94°. To test if there is a relationship between the hydrophobic properties of a surface and its ice formation capabilities, an experiment was designed to measure the time taken for a water droplet, placed on the abovementioned test plates of different hydrophobic properties, to freeze completely. Generally, the test plates that were etched using the 4M HCL etchant showed slower ice formation rates than those etched in 3M HCL etchant. Furthermore, comparing between contact angles and ice formation rates, it was found that the larger the contact angle produced, the slower the rate at which the water droplet freezes. As expected, the test plate that produced the largest contact angle of 155.94° had the slowest ice formation time of 8 minutes 16 seconds. In addition, it was also discovered that freezing of the test plates caused a degradation of contact angles which led to a deterioration of ice formation capabilities of the hydrophobic surfaces. A second round of the icing experiment showed an overall drop in ice formation rates than in the first round.