本研究以鳥類翅膀之小翼羽（Alula）與開衩翼尖（Slotted Wingtip）為靈感，探討其構造於拍撲翼非穩態條件下之流體力學效應。實驗採用具兩自由度之拍撲機構，分別控制翅膀之拍撲與旋轉運動，並搭配Mini40六軸力感測器進行氣動力量測，輔以粒子影像測速技術（Particle Image Velocimetry, PIV），觀察瞬時流場結構以及渦度分布，進一步探討拍撲運動中之流場行為。
在力量測方面，首先驗證開衩翼尖於拍撲運動中對升力與阻力之氣動效益，接著分析搭配小翼羽後之變化，最後探討三種不同開衩翼尖構型（平面M1、漸增上反角M2、對稱上反角M3）於不同攻角條件下之性能差異。根據實驗結果顯示，開衩翼尖可有效提升升力並降低阻力，進而改善整體氣動效率；小翼羽亦可於全攻角範圍內穩定提升平均升力。開衩翼尖構型方面，M1於攻角60°時展現最佳升力表現與穩定性，而M2於45°攻角下則具有升力強化潛力，但於更高攻角下穩定性較低。
進一步透過PIV流場觀測，發現M1與M2構型於其對應之過失速攻角（M1為60°、M2為45°）皆可在翼表面上發現穩定附著之翼前緣渦流結構（Leading-edge vortex, LEV），以維持升力表現；然而當攻角進入深度失速階段時，LEV則產生脫離與破碎現象，導致氣動性能快速下降。
綜合實驗結果可知，小翼羽與開衩翼尖在過失速攻角條件下展現顯著氣動優勢，不僅有助於提升升力，亦能穩定流場結構。期望本研究成果對於仿生拍撲翼之氣動優化與高攻角操作策略提供參考與設計依據。

This study investigates alula and slotted wingtips affect unsteady aerodynamics in flapping wings. A two-degree-of-freedom mechanism was built and tested in a water tank; aerodynamic forces were measured with a waterproof six-axis sensor, and instantaneous flow fields were visualized via particle image velocimetry (PIV). Angles of attack (AoA) of 30°, 45°, 60°, and 75° were selected to span pre-stall, post-stall, and deep-stall regimes. Three wingtip designs were compared while keeping planform, airfoil, and alula geometry fixed: M1(planar slotted wingtips), M2(gradual dihedral slotted wingtips), and M3 (symmetric dihedral slotted wingtips).
Force measurements show that slotted wingtips e provide a dual benefit, raising mean lift and lowering mean drag thereby improving overall flapping efficiency. Adding an alula yields a stable lift increase at all tested AoA with smooth, non-oscillatory lift histories. However, performance depends strongly on wingtip geometry: M2 achieves peak lift at 45° but loses stability by 60°, whereas M1 sustains higher lift and efficiency at 60° and remains more robust at 75°. M3 provides no clear advantage, producing higher drag and weaker lift overall.
Flow visualization clarifies the mechanisms underlying these trends. At effective operating points (M1 at 60°, M2 at 45°), a coherent, attached leading-edge vortex (LEV) forms and persists, sustaining lift and delaying separation. At higher AoA, the LEV detaches and fragments, marking deep stall and rapid performance degradation.
Overall, the findings demonstrate that alula-assisted lift augmentation and slotted-tip drag relief are most effective in the post-stall regime, while planar slots offer superior robustness at high AoA.

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