An Explorative Study to Use Super-Hydrophilic/Super-Hydrophobic Hybrid Surfaces for Aircraft Icing Mitigation 2019-01-1995

An explorative study was performed to demonstrate the feasibility of using a novel hybrid anti-/de-icing strategy for aircraft icing mitigation. The hybrid method was developed by combining the electro-thermal heating mechanism and specialized surfaces/coatings with different wettabilities. While an electrical film heater was utilized to provide thermal energy around the leading edge of a NACA0012 airfoil model, two different coating strategies, (i.e., (a). Superhydrophobic coating covering the entire airfoil surface to increase droplets bounce-off and accelerate surface water runback vs. (b). super-hydrophilic coating at the leading edge to increase evaporation area + superhydrophobic coating in downstream to prevent runback refreezing) were proposed and evaluated aiming at maximizing the anti-/de-icing efficiency of the hybrid method. While a series of experiments were conducted to examine the dynamics of droplet impinging onto the different surfaces (i.e., superhydrophobic vs. super-hydrophilic), a comprehensive experimental study was carried out in the Icing Research Tunnel at Iowa State University (i.e., ISU-IRT) to evaluate the anti-/de-icing performance of the hybrid method with the different coating strategies. It was found that, while both of the coating strategies could promote better anti-/de-icing performance of the hybrid method in comparison to the conventional heating-only method at rime ice condition. For glazed ice condition, the use of superhydrophobic coating over the entire airfoil surface would result in a maximized anti-/de-icing efficiency of the hybrid method (i.e., achieve a complete ice prevention with only 3% chord length covered with the electrical film heater), attributing to the significant droplets bounce-off and accelerated surface water runback behaviors.