03.2 - Experimental Aerodynamics
DESIGN, MANUFACTURING, AND TESTING OF HUMPBACK WHALE-INSPIRED TUBERCLES FOR ENHANCED LOW-REYNOLDS WING PERFORMANCE.
E. Barroso, instituto Nacional de Técnica Aeroespacial (INTA),, Spain; R. Bardera¹, J.C. Matías¹, J. Fernández¹, A.A. Rodríguez Sevillano, Universidad Politécnica de Madrid, Spain; ¹Instituto Nacional de Técnica Aeroespacial (INTA),, Spain
This paper presents an experimental wind tunnel study on the aerodynamic behavior of several
bioinspired wing configurations applied to a fixed-wing Small Remotely Piloted Aircraft System
(RPAS). The vehicle, specifically designed and manufactured to operate at low Reynolds numbers,
features a conventional configuration with a rectangular wing and a V-tail. The study is focused on
the aerodynamic advantages associated with the leading-edge tubercles found on the pectoral fins
of humpback whales, which have been widely reported to delay stall onset, increase lift force at high
angles of attack, and improve aerodynamic performance under low-speed flight conditions.
Building on these characteristics, the application of bioinspired geometries to small RPAS wings has
been investigated with the aim of enhancing aerodynamic efficiency, improving lift generation, and
delaying flow separation. Several leading-edge tubercle configurations were designed, modeled in
3D, and tested in a low-speed wind tunnel. In a first stage, an idealized geometry with constant
amplitude and wavelength along the wingspan was generated, corresponding to a regular sinusoidal
leading edge. Subsequently, a more realistic bioinspired configuration was developed by introducing
variable amplitude and wavelength, together with positive leading-edge sweep, in order to more
closely reproduce the morphology of the humpback whale fin.
The results were compared against a base rectangular wing, allowing the influence of leading-edge
tubercles on lift, drag, aerodynamic efficiency, and stall behavior to be assessed. The experimental
results show that, although the base wing provides better performance at low angles of attack, the
bioinspired configurations significantly improve the aerodynamic behavior near stall and post-stall
conditions. The conventional wing stalls at approximately 10∘, whereas the constant tubercled wing
delays stall up to around 15∘and the realistic humpback whale-inspired configuration up to
approximately 16∘, corresponding to stall-delay improvements of about 5 and 6 degrees,
respectively. At 12∘, the lift coefficient increases by approximately 11 % for the constant tubercled
wing and 9 % for the realistic configuration, while the aerodynamic efficiency improves by
approximately 11 % and 20 %, respectively. These results confirm the potential of leading-edge
tubercles as a passive flow-control strategy to improve the aerodynamic performance of small RPAS
operating at low Reynolds numbers.