Year: 2026
Type: article
Abstract: This study investigates the aerodynamic characteristics of a swallow-inspired wing based on a NACA 2415 airfoil at Reynolds numbers of 7.5 × 10 4 and 1.25 × 10 5 using experimental force measurements and flow-visualization techniques. The bioinspired wing model was designed according to the top-view geometry of a swallow wing and tested in a low-speed open-suction wind tunnel together with a rectangular wing of identical planform area and airfoil profile to provide a baseline comparison. Aerodynamic measurements were conducted over an angle-of-attack range between −6° and 24° to determine lift, drag and moment coefficients as well as aerodynamic efficiency. In addition to force measurements, smoke-wire and TiO 2 based flow visualization techniques were used to examine the flow topology around the test models. The results show that the swallow-inspired wing exhibits improved aerodynamic performance compared with the rectangular configuration under both Reynolds number conditions. At Re = 1.25 × 10 5 , the bioinspired wing achieved a maximum lift coefficient of 0.694 at an angle of attack of 9°, while the minimum drag coefficient was approximately 7.48 × 10 −3 . The aerodynamic efficiency reached a maximum L/D ratio of 42.9 at an angle of attack of 2°. Similar aerodynamic trends were observed at Re = 7.5 × 10 4 , although slightly reduced lift and aerodynamic efficiency were recorded due to stronger viscous effects at lower Reynolds numbers. The pitching moment coefficient varied approximately linearly with angle of attack, with a slope of −7.8 × 10 −3 per degree and a zero-lift moment value of −7.47 × 10 −3 , indicating stable longitudinal aerodynamic behavior. Flow visualization results revealed a gradual transition from attached laminar flow to separated turbulent flow, suggesting smoother stall development and improved flow stability for the bioinspired configuration. These findings highlight the aerodynamic advantages of swallow-inspired wing geometries and their potential to enhance aerodynamic efficiency in low Reynolds number flight.
Source: Bioinspiration & Biomimetics
Authors: K N Tekeoğlu, H Akbıyık, N F Tümen Özdil
Language: English
Subfield: Aerospace Engineering
Field: Engineering
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $3,325
Awards: G2698204565, G3957037266
OpenAlex ID: W7154992032