Computational study on the hovering mechanisms of a chordwise flexible wing

Abstract

The flexion effect of a flexible wing during the hovering flight is systematically studied by using computer simulations when Reynolds number is kept at 140. The aerodynamic forces and flow vortex are investigated by solving the two-dimensional time-dependent incompressible Navier-Stokes equations using the finite volume method. The wing is modelled as a thin plate which has a rigid leading portion and a flexible aft part. The simulations are performed for a variation of the location of rotational centre and the amplitude of the flexion, and the corresponding changes of the aerodynamic forces and vortex shedding mechanism in the wake structure are investigated. Form the quantitative comparisons, the present simulations reveal that a moderate flexion during the hovering fly can provide a better performance for a flapping wing, while an excessive flexion will lead the aerodynamic performance become worse. Though the flexion does not change the force trace of the hovering wing, the magnitude of the instantaneous peak forces and mean periodic forces are definitely changed by the chordwise deformation. Compared with a rigid hovering wing, the dynamic flexion during hovering alters the intensity of the leading edge vorticity and the transfer direction of the wake. Here, the present results indicate that the aerodynamic forces can be altered by adding some deformation characteristics to the trailing edge of the wing. Furthermore, the appropriate flexion can be used to alter the aerodynamic performance of a wing and will be helpful for design and control of the flexible microflying vehicles.

Time-Varying Wing-Twist Improves Aerodynamic Efficiency of Forward Flight in Butterflies

“…Despite the fact that the particular recording was chosen from a multitude of recordings and in our view, is a good representation of level forward flight, the generality of the findings is uncertain and a broad assessment of the effects of wing flexibility and deformation on flapping flight requires comparison of the current results to studies. In this regard, other recent work on deforming flapping wings has focused on the effects of chordwise (camber) deformation [17], [19], [28], [34]. However, our results indicate that wing twist plays a dominant role in deformation-induced enhancement of flight performance of the butterfly examined here.…”

Aeroelastic Analysis of Avian-Based Flexible Flapping Wings for Micro Air Vehicles

“…Though many computational studies have provided insight into the flapping wing phenomenon (Refs. 21,22), much of this work is limited by a two-dimensional (2D) flow environment, and simplistic aerodynamic and/or structural modeling. Malhan et al validated an aeroelastic solver with average force measurements for an MAV-scale flapping wing in forward flight (Ref.…”

The aerodynamic performance of a 2D lumped flexible airfoil in forward flight

“…On the other hand, Zhao et al 11 investigated the effect of chord-wise flexibility in an experiment using a dynamically scaled mechanical model of an insect wing and they concluded that flexible wings offer no aerodynamic advantage over a rigid wing under steady state circumstances. Zhang and Zhou 12 studied a hovering airfoil in a prescribed time-dependent flexible deformation and they investigated the effect of flexure amplitude and the location of rotational center on the unsteady aerodynamic characteristics where the Reynolds number was 140. The result demonstrated that a moderately flexible airfoil can provide better aerodynamic performance than a rigid airfoil.…”