A combined airfoil with secondary feather inspired by the golden eagle and its influences on the aerodynamics

Abstract

Bird flight is a remarkable adaption that has allowed thousands of species to colonize all terrestrial habitats. A golden eagle has impressive flying abilities, such as hovering, perching, preying and attacking. To reveal the flying abilities, avian geometry of a golden eagle was extracted based on noncontact surface measurements using a ROMBER three-dimensional laser scanner. Distributions of a camber line, thickness and a secondary feather line of the extracted point cloud were fitted using convenient analytical expressions. A traditional airfoil was established with the camber line and thickness, then a combined airfoil was constructed by combining the traditional airfoil with a secondary feather. Oscillations of an airfoil as well as rapid pitch up were simplified as a sine wave around the quarter chord axis. Thereafter, both steady and unsteady aerodynamic performances of the airfoil are computed, the influences of the secondary feather on the steady and unsteady aerodynamics were further studied.

Design Analysis of Vertical Axis Wind Turbine Blade Using Biomimicry

“…First, the foils NACA 0012, NACA 0015, NACA 0018, NACA 0022, NACA 4312 and NACA 4412 were selected. Asymmetric or non-cambered foils S809, S1012, S1210, DU 06 W200, FX 63 137, UO 17 LDA were chosen based on supporting VAWT blades [8,10]. Q-Blade was used to analyse the foils to find the best suitable and efficient foil structure under different wind conditions based on torque, lift and drag ratios.…”

“…Bio-mimicable features with aerodynamic capabilities worth incorporating into the dynamic VAWT blades using base foil FX 63-137 as the standard reference foil included the Golden Eagle wing, Dragon Fly wing, Maple seed leaf. Whereas the Golden Eagle wing structure and [7][8][9] Dragonfly vein structure are quite suitable for the sizable blade cross section, hence their design features were suitable for adding on the base foil [Figures 5, 6 and 7]. The corrugated pattern of the veins on dragon fly's transparent wings enables dragon flies to maintain fixed altitudes and swift flight trajectories for long durations of time without intervals helping them migrate great distances in short time periods.…”

“…Study of golden eagle wing geometry with secondary wing for aerodynamics was analysed in fluent. It fit the steady flow conditions with performance improvements at high pitch angles using secondary wing structure [8]. Flexible blade structure made of bamboo laminate with dragonfly vein corrugated add on was simulated and it gave the advantage of delayed stall and better adaptation over similar base foil structure [9].…”

Shape reconstructions and morphing kinematics of an eagle during perching manoeuvres*

“…[19] To considerate these flight feather effects, the enhancement of lifts and increasement of wing area s are included in Eqs. ( 11) and ( 12) based on the previous researches, [25]…”

“…As the deep stall, the drag can be enlarged to induce the loss of the total kinetic energy to the wake. [25] Both the high lift and the high drag offer the opportunity to change the flight attitude quickly.…”