Exploration of bio-inspired wingtip devices for low aspect ratio wing

Abstract

This study investigates the performance of low aspect ratio wing by incorporating bio-inspired wingtip devices, aiming to enhance the flying characteristics of micro air vehicles. The S5010 profiled wing, with an aspect ratio of 1.0, is selected as the reference wing. The wingtip devices are designed as flat plates, with a taper ratio of 0.5, featuring rounded leading and trailing edges. These devices are attached to the wingtip in a planar manner, thereby creating slots on the wingtip. Such an approach is intended to replicate the wingtip slot observed in the structure of primary feathers of soaring birds during flight, potentially providing aerodynamic benefits. In this study, four different winglet configurations are fabricated, and investigations are carried out in a subsonic wind tunnel at a Reynolds number range of 70000 to 110000. The results show significant improvements in lift slope, maximum lift coefficient, drag, lift-to-drag ratio, and pitching moment for all winglet configurations compared to the baseline. Furthermore, the study also investigates the effectiveness of winglet configurations by varying the number of attachments to the wingtip and their lengths. It is observed that configurations with a higher number of attachments show a more significant reduction in induced drag and upward pitching tendency than configurations with fewer attachments. Additionally, the performance of wing configurations is strongly affected by the Reynolds number, and it improves as the Reynolds number increases.