Dwarf Kingfisher-Inspired Bionic Flapping Wing and Its Aerodynamic Performance at Lowest Flight Speed

Abstract

This paper aims to understand the aerodynamic performance of a bio-inspired flapping-wing model using the dwarf Kingfisher wing as the bionic reference. The paper demonstrates the numerical investigation of the Kingfisher-inspired flapping-wing followed by experimental validation to comprehend the results fully and examine the aerodynamic characteristics at a flight velocity of 4.4 m/s, with wingbeat frequencies of 11 Hz, 16 Hz, and 21 Hz, at various angles of rotation ranging from 0° to 20° for each stroke cycle. The motivation to study the performance at low speed is based on lift generation as a challenge at low speed as per quasi-steady theory. The temporal evolution of the mean force coefficients has been plotted for various angles of rotation. The results show amplification of the maximum value for the cycle average lift and drag coefficient as the rotation angle increases. The history of vertical force and the flow patterns around the wing is captured in a full cycle with asymmetric lift development in a single stroke cycle. It is observed from the results that the downstroke generates more lift force in magnitude compared to the upstroke. In addition to the rotation angle, lift asymmetry is also affected by wing–wake interaction. Experimental results reveal that there is a stable leading-edge vortex developed in the downstroke, which sheds during the upstroke. An optimum lift and thrust flapping flight can be achieved, with a lift coefficient of 3.45 at 12°. The experimental and parametric study results also reveal the importance of passive rotation in wings for aerodynamic performance and wing flexibility as an important factor for lift generation.

Numerical Study of an External Flow around a Corrugated Wing using Lattice Boltzmann Method

“…The Lattice Boltzmann method emerged as a numerical alternative to the Navier-Stokes equations at macro and meso level computations. Now it has been extended to the realm of micro and nanofluidics Considering a mesoscopic model of a fluid, which is bounded by the incompressible Navier-Stokes equations ( 3) and ( 4) at the macroscopic level [20] and used for insect and bird flight [21,22], we have: The LBM is quite stable with less dissipation, as such makes it a suitable method to solve NS equations. One such example is the determination of the instantaneous flow field of the MAV rotor concerning the ground as shown in figure 3(b).…”

The Lift Effects of Chordwise Wing Deformation and Body Angle on Low-Speed Flying Butterflies

“…Experiments on PIV in biomimetic studies are often conducted on an object fixed at a particular point, such as a flapping mechanism [ 25 , 35 , 36 ] or an actual wing [ 18 , 33 , 37 ]. For analyses of the flow field of a real hovering insect, a living specimen is often fixed at a point [ 18 , 26 , 33 ].…”

Computational Fluid Dynamics Analysis in Biomimetics Applications: A Review from Aerospace Engineering Perspective

“…According to Singh et al [ 11 ], the unsteady flow dynamics induced the oscillation of aerodynamic force and moments of flying animals; thus, a mathematical model with nonlinearity should be considered. Abas et al [ 50 ] highlighted the use of predictive quasi-steady model approximation for the condition of unsteady aerodynamic forces that influenced rotation, translation, rotation-translation coupling, and the added-mass effect. The motion of the wing or fin can be implemented using time histories of attitude angles rotated with respect to three different axes of the local coordinate systems.…”