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PUBLISHED RESEARCH

Effect of different types of wing-wing interactions in flapping MAVs
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Tay, W. B. (2017). Journal of Bionic Engineering, 14, 60–74.

Wing-wing interaction (WWI), such as the clap and fling motion (CFM), occurs when two wings are flapping close together, improving performance. We intend to design a hovering flapping MAV (FMAV) which makes use of WWI. We want to investigate the effects of flexibility, kinematic motions, and two- to six-wing flapping configurations on the FMAV through numerical simulations. Results show that a rigid spanwise, flexible chordwise wing produces the highest lift, minimum power. The smoothly varying sinusoidal motion, which is visually similar to the CFM, produces similar lift in comparison to the CFM, while having lower peak power requirement. Lastly, lift produced by each wing of the two-, four-, six-wing configuration is approximately equal. Hence more wings generate higher total lift force, but at the expense of higher drag and power requirement. These results will be beneficial in the understanding of the underlying aerodynamics of WWI, and in improving the performance of our FMAV.

Projected radial vorticity on plane at radius = 0.7c with px2_pz2

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Clap and fling motion whereby span and chord both varies quadratically. Notice the weak Leading Edge Vortex (LEV), producing lower lift.

Projected radial vorticity on plane at radius = 0.7c with px1_pz2

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Clap and fling motion whereby span and chord varies linearly and quadratically respectively. Notice the large well-developed Leading Edge Vortex (LEV), producing higher lift.

Comparing between two types of clap and fling motion:

WWIM1 - clap and fling motion with impulsive acceleration and deceleration at endstroke

WWIM2 - clap and fling motion with sinusoidal acceleration and deceleration variations

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The graphs above show the thrust and lift variation of a single wing of WWIM1 and WWIM2 over a period. The high lift on the left graph for WWIM1 is due to the instantaneous high rate of rotation. In comparison, WWIM2 shows much gradual lift variation due to the smooth sinusoidal function. The table above shows that despite the difference in kinematics, their average thrust and lift are similar. WWIM1 may be less preferable compared to WWIM2 for FMAV design since it is more difficult to design and requires higher maximum power input.

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