Data from: Hovering hummingbird wing aerodynamics during the annual cycle

The diverse hummingbird family (Trochilidae) has unique adaptations for nectarivory, among which is the ability to sustain hover-feeding. As hummingbirds mainly feed while hovering, it is crucial to maintain this ability throughout the annual cycle—especially during flight-feather moult, in which wing area is reduced. To quantify the aerodynamic characteristics and flow mechanisms of a hummingbird wing throughout the annual cycle, time-accurate aerodynamic loads and flow field measurements were correlated over a dynamically scaled wing model of Anna’s hummingbird (Calypte anna). We present measurements recorded over a model of a complete wing to evaluate the baseline aerodynamic characteristics and flow mechanisms. We found that the vorticity concentration that had developed from the wing’s leading-edge differs from the attached vorticity structure that was typically found over insects’ wings; firstly, it is more elongated along the wing chord, and secondly, it encounters high levels of fluctuations rather than a steady vortex. Lift characteristics resemble those of insects; however, a 20% increase in the lift-to-torque ratio was obtained for the hummingbird wing model. Time-accurate aerodynamic loads were also used to evaluate the time-evolution of the specific power required from the flight muscles, and the overall wingbeat power requirements nicely matched previous studies.

物种丰富的蜂鸟科（Trochilidae）具有适配食蜜习性的独特适应性特征，其中一项核心能力便是维持悬停取食的本领。由于蜂鸟主要依靠悬停状态进食，因此在全年生命周期中维持该能力至关重要，尤其在飞羽换羽期，此阶段翅翼面积会出现缩减。为量化蜂鸟翅翼在全年生命周期中的气动特性与流动机理，研究团队以按比例动态缩放的安氏蜂鸟（Calypte anna）翅翼模型为研究对象，开展了时间精准的气动载荷与流场测量，并对二者进行关联分析。本研究呈现了完整翅翼模型的实测数据，以评估其基础气动特性与流动机理。研究发现，蜂鸟翅翼前缘形成的涡量聚集与昆虫翅翼常见的附着式涡结构存在显著差异：其一，涡量聚集沿翼弦方向更为细长；其二，该结构伴随剧烈脉动而非稳定涡旋。升力特性与昆虫翅翼相近，但安氏蜂鸟翅翼模型的升力扭矩比提升了20%。研究同时利用高精度气动载荷数据，评估了飞行肌肉所需的单位功率随时间的演化规律，整体振翅功率需求与此前的研究结果高度吻合。