Experimental Investigation of Flexible Hawkmoth-like Wings on the Wing-wake Interaction in Hovering Flight  

作　　者：YeongGyun Ryu Jo Won Chang Joon Chung Dong-Ha Kim 

机构地区：[1]Department of Aerospace Engineering, Ryerson University, Toronto, Ontario M5B 2K3, Canada [2]Department of Aeronautical Science and Flight Operation, Korea Aerospace University, 76, Hanggongdaehak-ro, Deogyang-gu, Goyang-si, Gyeonggi-do 10540, Republic of Korea [3]Aerodynamics Group, Korean Air R&D Center, Daejeon Metropolitan City 34054, Republic of Korea

出　　处：《Journal of Bionic Engineering》2018年第1期139-153,共15页仿生工程学报（英文版）

摘　　要：To study wing-wake interaction for various wing flexibilities, force measurements and digital particle image velocimetry were carried out on flapping hawkmoth-like wings in a water tank. Wing thickness was employed as a design variable for the wing flexi- bility distributions. Abrupt flap-down and phase delay in flexible wings influenced the behaviors of the Leading-Edge Vortex （LEV） and Trailing-Edge Vortex （TEV）, generated by the previous stroke. While the rigid wing exhibited a detached LEV at the end of the stroke, wing with specific flexibilities obtained attached LEVs. The attached LEVs induced a relatively rapid flow toward the wing surface as a result of encountering the TEV, and the flow caused a higher lift peak. On the other hand, the wings with larger wing deformations generated distinctive changes in LEV and TEV behaviors. The flap-down helped the TEV form closer to the wing surface, and it thus caused a downwash rather than wing-wake interaction. Furthermore, the most flexible wing had a newly-formed pair of LEVs above the wing during the wing reversal, thereby being not able to generate the wing-wake interaction. These results help to understand the different vortex structures generated by flexible wings during the wing reversal and the corresponding effects of wing-wake interaction.To study wing-wake interaction for various wing flexibilities, force measurements and digital particle image velocimetry were carried out on flapping hawkmoth-like wings in a water tank. Wing thickness was employed as a design variable for the wing flexi- bility distributions. Abrupt flap-down and phase delay in flexible wings influenced the behaviors of the Leading-Edge Vortex （LEV） and Trailing-Edge Vortex （TEV）, generated by the previous stroke. While the rigid wing exhibited a detached LEV at the end of the stroke, wing with specific flexibilities obtained attached LEVs. The attached LEVs induced a relatively rapid flow toward the wing surface as a result of encountering the TEV, and the flow caused a higher lift peak. On the other hand, the wings with larger wing deformations generated distinctive changes in LEV and TEV behaviors. The flap-down helped the TEV form closer to the wing surface, and it thus caused a downwash rather than wing-wake interaction. Furthermore, the most flexible wing had a newly-formed pair of LEVs above the wing during the wing reversal, thereby being not able to generate the wing-wake interaction. These results help to understand the different vortex structures generated by flexible wings during the wing reversal and the corresponding effects of wing-wake interaction.

关 键 词：hovering flight flexible hawkmoth wings wing-wake interaction Digital Particle Image Velocimetry （DPIV） 

分 类 号：Q[生物学]