The winglets located at aircraft wing ends are used to increase the aerodynamic performance and reduce fuel consumption by regulating negatively affecting the performance at the wings end. Therefore, aircraft wings have a critical importance on aerodynamic efficiency. The most efficient winglet model should be used in each of the flight positions. This study is aimed to investigate the effects of concave, convex, and plain winglet geometry on wing performance. The effects of plain, concave and convex winglet models with cant angles of 30°, 45°, and 60° were experimentally investigated at the angles of attack ranging from 0 to 20°. The aerodynamic lift and drag coefficients generated by each design were measured in wind tunnel tests conducted at a Reynolds number of 2.5 × 105, and the effect of the winglet’s shape on wing performance was compared. The data obtained reveal that various wingtip designs have significant effects on the aerodynamic properties of the wing. At low, moderate and high angles of attack, the highest lift is achieved with the 30° cant angle winglet. The best results for all winglet models in terms of the aerodynamic quality were obtained in the plain winglet model. Furthermore, the aerodynamic quality generally increases with decrease in the cant angles. It is anticipated that these findings, obtained from winglet models with various geometric designs, could contribute to the development of more efficient winglet geometry.
Zerlen et al. (Sun,) studied this question.