Three-dimensional wing structure attenuates aerodynamic efficiency in flapping fly wings
Three-dimensional wing structure attenuates aerodynamic efficiency in flapping fly wings
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DOI：
10.1098/rsif.2019.0804
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发表时间：
2020-03-25
影响因子：
3.9
通讯作者：
Lehmann, Fritz-Olaf
中科院分区：
文献类型：
--
作者：
Engels, Thomas;Wehmann, Henja-Niniane;Lehmann, Fritz-Olaf
飞行昆虫的空中表现最终取决于扑翼如何与周围空气相互作用。以前曾有人建议，机翼的三维曲面和曲率有助于在扑翼运动过程中克服空气动力学和惯性载荷。然而，它们对气动力产生的贡献仍在讨论中。在这里，我们研究了三种不同大小的苍蝇使用模型的微型计算机断层扫描的自然翅膀和模型中，我们删除了机翼的弧度，弯曲，或两个属性的三维机翼形状的潜在好处。从三维计算流体动力学模型中推导出了根部拍动过程中的力和气动功率需求。我们的数据表明，与平翼相比，三维弯度对升力的产生没有好处，并且使朗肯-弗劳德飞行效率降低了大约12%。此外，我们没有发现证据，在雷诺数137和1623之间的升力增强被困涡的山谷。然而，我们发现，在所有测试的昆虫物种，扑翼过程中的气动压力分布是紧密对齐的翅膀的脉络模式。总而言之，我们的研究有力地支持了这样一个假设，即机翼的三维结构提供了对抗外力的机械支撑，而不是提高升力或节省与主动扑翼相关的能量成本。
The aerial performance of flying insects ultimately depends on how flapping wings interact with the surrounding air. It has previously been suggested that the wing's three-dimensional camber and corrugation help to stiffen the wing against aerodynamic and inertial loading during flapping motion. Their contribution to aerodynamic force production, however, is under debate. Here, we investigated the potential benefit of three-dimensional wing shape in three different-sized species of flies using models of micro-computed tomography-scanned natural wings and models in which we removed either the wing's camber, corrugation, or both properties. Forces and aerodynamic power requirements during root flapping were derived from three-dimensional computational fluid dynamics modelling. Our data show that three-dimensional camber has no benefit for lift production and attenuates Rankine-Froude flight efficiency by up to approximately 12% compared to a flat wing. Moreover, we did not find evidence for lift-enhancing trapped vortices in corrugation valleys at Reynolds numbers between 137 and 1623. We found, however, that in all tested insect species, aerodynamic pressure distribution during flapping is closely aligned to the wing's venation pattern. Altogether, our study strongly supports the assumption that the wing's three-dimensional structure provides mechanical support against external forces rather than improving lift or saving energetic costs associated with active wing flapping.