Effect of flapping trajectories on the dragonfly aerodynamics
chuangxin zhao2006, Chinese Science Bulletin
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Abstract
The effects of translational, figure-eight and double-figure-eight flapping trajectories on the dragonfly aerodynamics were numerically studied by solving the Navier-Stokes equations. There is a common characteristic regarding the lift/drag force coefficients that the downstroke flapping provides the lift forces while the upstroke flapping creates the thrust forces for different flapping trajectories. The maximum lift force coefficient exceeds five for the translational trajectory. It is greater than six for the figure-eight and double-figure-eight flapping trajectories, which is sufficiently larger than unity under the steady state flight condition. The ellipse and double-figure-eight flapping trajectories yield the decrease of the lift force, while the figure-eight flapping trajectory yields higher lift force as well as the thrust force than the translational flapping one. During the insect flight, the wing flapping status should be changed instantaneously to satisfy various requirements. Study of the flapping trajectories on the insect aerodynamics is helpful for the design of the Micro-air-vehicles (MAVs).
Key takeaways
- In order to understand the effect of the horizontal deviation motion on the insect aerodynamics, we computed the lift/drag forces for several flapping trajectories (the translational, ellipse and figure-eight flapping trajectories).
- Strictly speaking, the wing cross section flapping plane, the m 1 m 2 plane, is an arc plane with the arc center located on the wing root.
- Thus for the present two-dimensional wing flapping motion, one mass and two momentum equations consisting of three unknown variables are closed, which can be solved under the given initial and boundary conditions.
- The wing flapping cycle period T=0.025 s. provided during the wing downstroke and the drag forces are mainly coming from the wing upstroke ( Fig. 5 only illustrates the lift/drag force coefficients for the translational and figure-eight flapping trajectories).
- Via the present numerical simulations it is found that the insect lift/drag force coefficients are greatly influenced by the flapping trajectories.
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