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RISS 인기검색어
- 검색키워드
- 저자 : Koji Isogai (검색결과 2 건)
- 무료
- 기관 내 무료
- 유료
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Development of a Resonance Type Flapping Wing for a Dragonfly-Type Micro Aerial Vehicle
Koji Isogai,Kazuya Maesato,Yuichi Kamisawa,Kenji Sato 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
The paper presents the development of resonance type flapping wings for a dragonfly-type micro aerial vehicle. which show high performance in spite of their simple structures and light weight. The wings (fore- and hind-wings) are composed of a single carbon rod of 1 ㎜ diameter and the thin EPP (Expanded Polypropylene) plate of 1.5 ㎜ thickness for the fore-wing and 3.0 ㎜ thickness for the hind-wing, respectively. The semi-span lengths of the wings are 0.11 m. The planforrns of the fore- and hind-wings are those of Onychogomphus viridicastus. The mass of the fore-wing is 0.25 g and that of the hind-wing is 0.30 g. The first natural frequencies of the fore- and hind-wings are 39 Hz and 47 Hz, respectively. The detailed performance of the wings such as time mean thrust and necessary power in still air (hovering condition) are measured using the vibration test bed. For example, the thrust is 0.095 N for the fore-wing and 0.111 N for the hind-wing at the frequency of 40 Hz. This means that the dragonfly-type MAV which employs the two-pairs of those flapping wings can generate the lift of 0.41 N (in hovering condition) at 40 Hz. In order to confirm this, a hovering demonstrator (mass: 40 g) which employs the present two pairs of the wings was built and tested. verifying that it can generate the lift which is larger than its own weight at flapping frequency of 40 Hz. The paper also presents the results of the numerical simulations of those flapping wings using a 3D Navier-Stokes code which takes into account aeroelastic effects.
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Experimental Study of Wing-Wake Interactions of Insect Flapping Wing
Hiroto Nagai,Koji Isogai,Tatsumi Fujimoto 한국항공우주학회 2008 한국항공우주학회 학술발표회 논문집 Vol.- No.-
An experimental study is conducted to investigate wing-wake interactions of a flapping wing of an insect in hovering and forward flight. Unsteady aerodynamic forces acting on a flapping wing are measured using a dynamically scaled mechanical model in a water tunnel, which simulates hovering and forward flapping flight of insects. In addition, flow visualization is made around the scaled flapping wing model using digital particle image velocimetry (DPIV). A flapping wing experiences wing-wake interaction that the wing interacts with the wake induced in the previous stroke, called wake capture. We investigate effects of parameters of a flapping wing on the wake capture. The results indicate that the wake capture is principally dependent on the two parameters: reduced frequency and timing of feathering rotation. And the flow visualization shows that the vortex pair with counter-rotating, which induces a strong jet flow between the two vortices themselves, enhances wake capture effect. The wake capture effect in forward flight appears in a different manner from in hovering flight. While the wake capture is more effective in the stroke reversal from the down- to up-stroke, it is slight effective in the stroke reversal from the up- to down-stroke.
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