Design of Hybrid Airfoils for Icing Tunnel Tests Based on Reduced-Order Modeling Methods

A hybrid airfoil is a scaled model for generating a full-scale ice shape for icing wind tunnel tests. This is possible by matching full-scale properties such as the distributions of collection efficiency and heat transfer coefficient. Previous studies have used indirect methods using full-scale stagnation point location or tangent droplet trajectories. Therefore, these methods can cause a discrepancy between the full-scale and hybrid airfoil ice shapes under glaze ice conditions. To cope with the issue, this paper proposes a new approach to match the distributions of the full-scale collection efficiency and heat transfer coefficient on the leading edge, using a viscous turbulent computational fluid dynamics icing simulation. For computational efficiency, reduced-order modeling based optimization was used to match the distributions. The optimization process was applied to the glaze ice condition with a high liquid water content and temperature. The results indicate that matching the distribution of the heat transfer coefficient is recommended to minimize the error between full-scale and hybrid airfoil ice shapes for the glaze ice condition. Finally, a hybrid airfoil flap geometry, which can be applied to various angles of attack, was designed using the optimization design process.