Ice accretion effect on the aerodynamic characteristics of long-endurance, high-lift airfoil design for UAV

This research utilizes numerical methods to evaluate ice accretion effects on the aerodynamic characteristics of airfoils designed for UAV application, especially on the effects of leading edge ice accretion. The thickness, length, and position of ice accretion and basic airfoil shapes are the parameters to be studied. The results show that when the ice thickness increases the lift coefficient, stalling angle, and maximum lift coefficient are seriously impaired for the three UAV airfoils used in this study. The lift coefficient and stalling angle decrease when the length of ice accretion increases. On the icing position, if ice accretion concentrates more on the leading edge its effect on the maximum lift coefficient is more pronounced than the case that ice spreads more evenly on the fore part of the airfoils. All three airfoils calculated show similar trend of performance deterioration, but the airfoils, GA-17 and NLF-1015, are less influence by ice accretion than the airfoil, TYPE A. When compared with the airfoils, NLF-1015 and TYPE A, the GA-17 airfoil designed by using genetic algorithm still have maximum C1/Cd)max and ΔC1/Cd)max under icing conditions. Ice formed on the upper leading edge has more detrimental effects than that formed on lower leading edge. This research results indicate that the icing effects can be minimized if it is taken into consideration during the airfoil design stage. The results of the paper can be used in future airfoil optimization work. For the UAVs designed to loiter under low Reynolds number conditions, their wings must not only have high lift and low drag coefficients but maintain high maximum lift coefficients under all weather conditions to safeguard their mission success.