Grant: Collaborative Research and Development Grants

This project is the continuation of a one-year project on ""Ice-phobic evaluation of superhydrophobic coatings for aircraft icing protection"". The devised superhydrophobic coated (SHC) small scale airfoil showed promising performance in both anti- and de-icing modes. It was demonstrated that for fully evaporative case, using SHC airfoil provides up to 75% savings on heat input. This proposed project is aimed at improving the technology readiness level (TRL) from 2 to 4 through a combined numerical and experimental study. The absence of fundamental understanding of the drop/surface interactions, especially in the presence of an air shear flow, has made it difficult to achieve proper coating development. The proposed experimental/numerical study is different from past investigations in that it takes a comprehensive approach to the issues of coatings, not only from the point of view of application, fabrication and icing characteristics, but also that of water drop dynamics on surfaces. It will specifically focus on drop interactions with superhydrophobic surfaces in static and dynamic (impact) conditions. Untreated aluminum surface currently in use will also be investigated to establish a baseline. Initially the study will focus on sliding behavior of stationary drops using flat coupons made of various superhydrophobic surfaces. This study will be extended to study the sliding behavior of a drop after its impact on the flat surface (i.e. the dynamics of drop impact on surfaces with various hydrophobicities). Alongside the experimental program, a numerical model of a drop impacting on a surface will also be developed which will use the static and dynamic contact angle information generated from experimental studies to examine surface treatments. We will use the proven method of Volume of Fluid (VOF) in order to model the deformation of liquid-gas interface as well as the solidification and phase change. Learned principles from these model studies will be applied to case of an airfoil in an attempt to generate recommendations for application of superhydrophobic coating for wings and nacelles. In addition, wear and erosion mechanisms for SHC will be extensively studied to improve its longevity in terms of UV and dirt exposure.