CAREER: Aerial and Aquatic Flapping Flight at Low Reynolds Numbers

拍动翅膀是小型动物在空气和水中常见的运动技巧。昆虫扇动翅膀在空中飞行，被称为海蝴蝶的浮游动物海蜗牛扇动翅膀状的附属物（称为旁足）在水中“飞行”。此外，一些微小的昆虫物种能够通过拍打翅膀在空气和水中移动。尽管空气和水的密度相差数千倍，但这些截然不同的动物的飞行系统在翅膀的运动方式和产生升力的方式上却惊人地相似。这些相似之处指向了设计一种能够进行空中和水上扑翼飞行的仿生微型飞行器的可能性，但这种飞行系统的流体动力学尚未得到很好的理解。这个项目的目的是研究小型生物扑翼系统在空气中、水中和两者中飞行的流体动力学。这项研究将在一个教育项目的大背景下进行，在这个教育项目中，代表性不足的工程专业学生通过学习研究技能、创作一本关于海蝴蝶的插图儿童书籍、参加研究生班的实地考察，为研究生学习做准备。微小的昆虫和海蝴蝶（翼足类动物）分别使用类似的翅膀运动学和升力产生技术来推动自己在空气和水中。此外，有些昆虫既用翅膀在空中飞行，也用翅膀在水中游泳。然而，无论是低雷诺数下空中和水中拍打运动的流体动力学，还是这些动物在空气、水中或两者中飞行的适应性，都没有得到很好的理解。本项目将通过实验研究这些适应性以及不同昆虫和翼足类动物在空气、水中拍打飞行的潜在流体物理，并得出以下结果：1)对游动翼足类动物进行高速运动学和体积流测量，将显示极端的翅膀灵活性如何影响升力产生。2)一种新型的超高速粒子图像测速系统将提供微小昆虫自由飞行所使用的三维运动学和所产生的流量的测量。3)微小水生昆虫游泳和飞行的运动学和流量测量将揭示空中飞行系统如何适应水生操作。这些结果将阐明这种运动技术的核心流体动力学原理，建立对动物在空气和水中拍打运动的适应性的理解，并启发多模式微型飞行器的设计策略。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

The flapping of wings is a common locomotion technique for tiny animals in both air and water. Insects flap their wings to fly in air, and zooplanktonic marine snails called sea butterflies flap wing-like appendages (called parapodia) to "fly" in water. Further, some tiny insect species are able to locomote via wing flapping in both air and water. Despite the thousand-fold difference in density between air and water, the flight systems of these very different animals show surprising similarities in how the wings move and in how they generate lift. These similarities point towards the possibility of designing a bio-inspired micro-aerial vehicle capable of aerial and aquatic flapping flight, but the fluid dynamics of such flight systems are not well understood. The aim of this project is to investigate the fluid dynamics of small-scale biological flapping systems flying in air, in water, and in both. This research will occur within the larger context of an education program in which underrepresented engineering students prepare for graduate studies by learning research skills, creating an illustrated children's book about sea butterflies, and attending a graduate class field trip.Tiny insects and sea butterflies (pteropods) use similar wing kinematics and lift generation techniques to propel themselves in air and water, respectively. Further, some insects use their wings for both aerial flight and aquatic swimming. However, neither the fluid dynamics of aerial and aquatic flapping locomotion at low Reynolds numbers nor the adaptations these animals have made to fly in air, water, or both are well understood. This project will experimentally investigate these adaptations and the underlying fluid physics of flapping flight in air, water, and both by a diverse group of insects and pteropod species, with the following outcomes: 1) High speed kinematics and volumetric flow measurements of swimming pteropods will show how extreme wing flexibility affects lift production. 2) A novel, ultra-high-speed particle image velocimetry system will provide measurements of the 3D kinematics used by and the flow generated by freely flying tiny insects. 3) Kinematics and flow measurements of the swimming and flying of tiny aquatic insects will reveal how an aerial flight system can be adapted to aquatic operation. These outcomes will illuminate the core fluid dynamics principles underlying this locomotion technique, build understanding of the adaptations animals have made for flapping locomotion in air and water, and inspire design strategies for multimodal micro-aerial vehicles.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.