Wing flexibility effect on aerodynamic performance of different flapping wing planforms

Addo-Akoto, Reynolds; Yang, Hyeon-Ho; Han, Jong-Seob; Han, Jae-Hung

doi:10.1016/j.jfluidstructs.2023.104006

Cited by 3 publications

(2 citation statements)

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“…The wing planform was designed from a 2 mm thick acrylic plate. The trailing-edge wing shape was the same as that of insect-like [23] and bird-like [24] MAVs and has recently been reported to generate higher lift in comparison with tip and rootweighted wings [25]. The LE curvature was described with an elliptic distribution since it creates a symmetry in the curvature about the mid-chord.…”

Section: Experimental Setup and Proceduresmentioning

confidence: 73%

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Leading-edge curvature effect on aerodynamic performance of flapping wings in hover and forward flight

Addo-Akoto,

Han,

Han

2024

Bioinspir. Biomim.

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This study investigates the role of leading-edge (LE) curvature in flapping wing aerodynamics considering hovering and forward flight conditions. A scaled-up robotic model is towed along its longitudinal axis by a rack gear carriage system. The forward velocity of the robotic model is changed by varying the advance ratio J from 0 (hovering) to 1.0. The study reveals that the LE curvature has insignificant influence on the cycle-average aerodynamic lift and drag. However, the time-history lift coefficient shows that the curvature can enhance the lift around the middle of downstroke. This enhanced lift is reduced from 5% to 1.2% as J changed from 0 to 1.0. Further flow examinations reveal that the LE curvature is beneficial by enhancing circulation only at the outboard wing sections. The enhanced outboard circulation is found to emanate from the less stretched leading-edge vortices (LEVs), weakened trailing-edge vortices (TEVs), and the coherent merging of the tip vortices (TVs) with the minor LEVs as observed from the phase-lock planar digital particle image velocimetry (DPIV) measurements. The far-wake observation shows that the LE curvature enhances the vorticity within the TV, helping to reduce the overall flow fluctuations in the far field. These findings can be extended to explain the predominantly straight LE wing shape of most flapping fliers with a small amount of curvature only observed near the wing tip.

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Section: Experimental Setup and Proceduresmentioning

confidence: 73%

“…At r * = 1 (wing tip), the results confirm the stronger TV vorticity produced by the curved LE wing. A qualitative description of the downwash patterns shows tip-weighted orientation, which exists for rigid wings in hover [25]. However, the symmetric effect from J = 0.25 drastically reduced the severity of the tip-oriented pattern.…”

Section: Flow Visualizationmentioning

confidence: 91%