Executive Summary : | Icing and frost formation are the major challenges in many parts of the world and cause inconvenience to daily life as well as damage to properties. Some of the common problems encountered are accidents caused by slippery roads, ice accretion of aircraft in freezing rain or by the intercept of supercooled water droplets, collapse of transmission lines and power network towers due to icing, frost formation on pipelines, damage to turbine blades and production loss due to ice accretion on wind turbines. Superhydrophobic surfaces are found to be a potential solution to ice accretion. However, the aircraft wing ice accretion due to the supercooled drops from the clouds is a complex phenomenon under extreme environmental conditions. Most of the studies are done on isothermal conditions at low Weber number impact situations at normal atmospheric conditions. However, the dynamics and subsequent freezing dynamics will be highly influenced by the degree of supercooling of the droplet, ambient and surface temperature, pressure and relative humidity conditions. It is therefore important to stimulate and mimic the real operating situations to test the efficacy of such superhydrophobic surfaces under such controlled environmental conditions in effective anti-icing. In this study, a controlled environmental system with independent controlling capability will be designed and developed with an arrangement to generate the supercooled drop. The drop impact dynamics and subsequent icing dynamics on the in-house developed superhydrophobic surface attached to a Peltier unit will be analyzed using high-speed imaging and Infra-Red (IR) imaging. Also, the current project evaluates the dynamic response of the droplet such as effective viscosity during the spreading of the lamella using the novel optical diagnostic experimental strategy by using a Position Sensitive Device (PSD. This would enable to develop a correlation for the maximum spreading and contact time based on the measured effective property. Establishing these comprehensive connections with the operating conditions under controlled environmental situations can provide a powerful platform for the development of a novel ice accretion map for aerospace or aircraft wing icing and develop strategies for anti-icing and de-icing. |