- 學位論文
拍撲平面傾斜角對豆娘前飛之空氣作用力影響
The Influence of Stroke-Plane-Angle on Aerodynamic Force of a Damselfly During Forward Flight
摘要
本文探討豆娘在前飛時，改變拍撲平面傾斜角控制飛行斜率之機制，結果可應用於拍撲翼式微飛行器之飛行操控設計。本研究以高速攝影機正交攝影法量測真實豆娘在自由飛行情況下之翅膀拍撲動作，結果顯示，傾斜角與飛行斜率具有密切相關性，且可以歸納出兩種改變傾斜角方式，模式一為固定前翅傾斜角25°，僅改變後翅傾斜角(30°至50°)；模式二為前、後翅以相同傾斜角同時改變(30°至48°)，利用量測所得翅膀動作建立三維非穩態數值模擬，並透過改變前、後翅之拍撲平面傾斜角，探討傾斜角對於空氣作用力影響機制進而操控飛行。 模擬結果顯示高傾斜角時，推力增加，垂直力減少，單位週期之平均推力增大，垂直力減小；低傾斜角時，推力減小，垂直力增加，單位週期之平均推力減小，垂直力增大，自由飛行模擬之軌跡顯示高傾斜角時飛行斜率低，低傾斜角時飛行斜率高，飛行斜率與傾斜角呈高度相關，說明拍撲平面傾斜角是能夠有效控制空氣作用力的參數，另外，模擬流場亦顯示前翅脫離之渦漩會影響後翅而產生交互作用，後翅在下拍階段，翼面受到前翅脫離之渦漩影響，上下翼面壓差下降，由於下拍時主要產生阻力與垂直力，翼面壓差降低，雖能夠減弱阻力之產生，卻也造成垂直力減弱，交互作用對於單位週期之平均推力增加約20%，而單位週期之平均垂直力減少約15%，而前後翅交互作用與前翅傾斜角之大小有關，前翅傾斜角低時，脫離之渦漩較容易影響後翅，而前翅傾斜角高時，脫離之渦漩位置較遠，對於後翅產生之影響較小。 本研究提出傾斜角與飛行斜率之關係，並解釋傾斜角對於飛行操控之影響機制，亦探討不同傾斜角模式對於前後翅交互作用之影響，未來在微飛行器設計上，可以應用本研究所提出之傾斜角與飛行斜率之關係，作為飛行操控之設計。
並列摘要
In this study, we used high-speed cameras to measure the motions of flapping-wings of damselflies in the case of free flight (forward flight). The results showed that the stroke-plane-angle (β) was closely correlated with the flight slope, and two modes of β of wings could be concluded. In first mode, βforewing is fixed at 25°, while βhindwing is between 30° and 50°. In the second mode, βforewing and βhindwing is the same. Using the measured wing motions, a 3-D numerical simulation was established, and the influence of the stroke-plane-angle on aerodynamic force was investigated by changing β in simulation. The simulation results showed that the wing at a higher β would generate larger horizontal force and lower vertical force. Lower β would generate lower horizontal force and larger vertical force. The trajectory of free flight simulation showed that the flight slope is highly correlated with β, which indicated that the adjustment of β is an effective way to control the aerodynamic force. In addition, the flow field also showed that the difference between different modes is the influence of wing-wing interaction. In first model, the surface of hindwing is affected by the vortex from the forewing during the downstroke, resulting in the pressure difference of the upper and lower surface dropping, so the vertical force and Negative horizontal force is weakened. Wing-wing interaction increased the average of horizontal force by 20% in a period and decreased vertical force by 15 % in a period. In second mode, since the forewing and hindwing flapped at the same stroke-plane-angle, the hindwings were less affected by the vortex from the forewings, and the influence of the wing-wing interaction on horizontal force and vertical force in a period was less than 10 %. This study explained the influence of stroke-plane angle on aerodynamic force. The results can be applied to the design of flight control of MAVs.