Aerodynamic investigation of Passer domesticus inspired biomimetic wing at low Reynolds number

Abstract

A biomimetic wing is designed by considering the wing of a natural flyer (Passer Domesticus) as a reference. Since the birds have thin wings, Bergey BW-3, a thin and highly cambered airfoil, is used to design wing’s cross-section. To investigate the aerodynamic characteristics of biomimetic wing, numerical and experimental studies are carried out at low Reynolds number (Re) ranging from 2.5x10^4 to 1x10^5. The performance of biomimetic wing is compared with rectangular and elliptical wings at Re = 5x10^4. It is observed that the separation bubble formed over the surface of biomimetic wing at Re = 2.5x10^4 is not strong enough to influence the lift coefficient but dramatically increases the drag coefficient when the mean angle of attack exceeds 18^0. It is observed that the drop in lift coefficient of rectangular wing is higher than that of other wings due to presence of sharp edges in the planform. The lowest drag coefficient is witnessed in elliptical wing but it also has lowest lift coefficient due to the interaction between the separation bubble and tip vortices. But the biomimetic wing offers highest lift coefficient with a considerable amount of drag. It is observed that the flow separates dramatically as the mean angle of attack increases beyond the stall angle in rectangular and elliptical wings. But a delay in the flow separation is observed in case of biomimetic wing after the stall angle. It is also observed that the suction over the wing surface of biomimetic wing is more at wingroot than that at wingtip, which may provide good stability during flight conditions. The enhanced aerodynamic performance of the biomimetic wing is due to change in shape of the wing along the span which has a strong influence over its effective angle of attack with respect to the incoming flow.

Unsteady aerodynamics of plunging cambered foil at low Reynolds number

“…Likewise, a lot of numerical and experimental investigations were carried out to assess the aerodynamic performance of the different wings/airfoils at different conditions. [9][10][11] Most of the studies are focussed on investigation of aerodynamic performance of symmetric airfoils like NACA 0012 during plunging motion. 12 There are a few investigations reported on cambered airfoils but those were concentrated on applications over wind turbine blades and had less interest towards MAV applications.…”