Effect of Wing Rotation and Phase Lag on Flapping Flight of Damselflies
Date Issued
2015
Date
2015
Author(s)
Hsieh, Tian-Fu
Abstract
This study is aimed to investigate the flapping fight of damselfly species Psolodesmus mandarinus and Mnais tenuis. By experimental observation and numerical simulation with fluid-structure interaction and dynamic mesh technique, we found out that damselfly can increase lift force by rotating their wing on flapping flight. The results can be applied on the design of biomimetic flapping mechanism and micro aerial vehicle. In the experiment, damselflies free-fly in acrylic chamber. High speed camera is used to capture the flapping motion and flow field while two dimensional PIV technique shows the interaction between the motion and vortex structure. In motion analysis, both species of damselflies utilize forward rotation, then adding this rotation motion into the numerical simulation. Comparing three kind of flapping motion, non-rotation, forward rotation, and backward rotation, while tandem wing has 0 degree phase lag. Results show that wing rotation changes wing surface area on horizontal and vertical direction. Flapping with rotation decrease lift force and increase drag force on each stroke but considering a whole flapping period, forward rotation can generate positive lift force and negative drag force which is thrust. Leading edge vortex and low pressure area on wing surface of backward rotation are stronger during up-stroke. It causes generating of negative lift force, however, forward rotation can decrease negative lift force during up-stroke. Therefore, It promote mean lift force greatly in a whole flapping period and can generate thrust during up-stroke. The result shows that why damselflies utilize forward rotation in stead of backward rotation on their flapping flight.
Subjects
amselfly
leading edge vortex
flapping flight
wing rotation
vortices interaction
Type
thesis
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