ERI: Free surface and flexibility effects in partially-submerged bioinspired propulsion

ERI：部分浸没仿生推进中的自由表面和灵活性效应

• 批准号: 2347477
• 负责人: Leah Mendelson
• 金额: $ 19.74万
• 依托单位: Harvey Mudd College
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-04-01 至 2026-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2347477&HistoricalAwards=false
• 关键词: ERI; Free; surface; flexibility; effects

Organisms often have specialized strategies for movement at the water’s surface. Their locomotion addresses unique constraints including surface waves, splashing, and reduced force production in air, which is a thousand-fold lower density than water. These behaviors present unique design opportunities for underwater vehicles, with applications including water-to-air take-off, maneuvering, and near-surface station-holding. Despite the prevalence of these biological examples, new information is needed about how bioinspired flapping propulsion performs while partially submerged. This work focuses on understanding the influence of the water’s surface on partially submerged propulsive performance. Beyond underwater vehicles, this work also helps explain the biomechanics of near-surface locomotion and aquatic jumping. This project will train an interdisciplinary team of undergraduate students in hands-on research problem solving. The project will also support a bioinspired design workshop for undergraduate anthropology and design students and an engineering workshop for women high school students in Southern California.This work experimentally investigates the roles of and interactions between the free surface and propulsor flexibility during partially submerged bioinspired flapping. Specific objectives are to determine: (1) How propulsive performance scales with the size and speed of the surface disturbance created by the flapping motion. (2) How the free surface deforms during partially submerged flapping motions, including the effects of flexibility on the surface behaviors observed. (3) How three-dimensionality, including finite widths, spanwise bending, and surface disturbances, affects partially submerged propulsive performance. Combined, these objectives provide new understanding about the role of the free surface in partially submerged propulsion. Objectives will be addressed by testing flexible plates that are simultaneously flapping and traveling vertically out of the water. Key variables include flapping frequency and amplitude, vertical velocity, plate stiffness, and aspect ratio. Multi-axis force and torque measurements will facilitate comparisons of thrust and efficiency. Performance trends will be scaled based on the size and speed of the surface disturbance, in addition to parameterizations based on the flapping kinematics. To explain performance trends, high-speed imaging will visualize the free surface dynamics (including air cavity and wave formation, splashing, and the extents of the disturbance) and particle image velocimetry will be used to compare wakes. For cases where performance differs between aspect ratios, 3D imaging of the propulsor shape will be leveraged to explain these observations. Additionally, the project will contribute to open-access tools for volumetric flow imaging, with materials publicly disseminated through an open-source project.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.

生物体通常有专门的策略在水面上移动。它们的运动解决了独特的限制，包括表面波，飞溅和减少空气中的力产生，空气的密度比水低一千倍。这些行为为水下航行器提供了独特的设计机会，其应用包括水对空起飞，机动和近水面站保持。尽管这些生物学的例子很普遍，但我们需要新的信息来了解生物启发的扑翼推进在部分淹没时的表现。这项工作的重点是了解水的表面上的部分淹没推进性能的影响。除了水下航行器，这项工作还有助于解释近水面运动和水上跳跃的生物力学。这个项目将培养一个跨学科的本科生团队，在动手研究解决问题。该项目还将支持一个生物启发设计研讨会的本科生人类学和设计的学生和一个工程研讨会的女高中生在南加州。这项工作实验研究的作用和自由表面之间的相互作用和推进器的灵活性在部分淹没生物启发扑翼。具体目标是确定：（1）推进性能如何与扑翼运动产生的表面扰动的大小和速度成比例。(2)自由表面在部分淹没的扑翼运动中如何变形，包括柔性对所观察到的表面行为的影响。(3)包括有限宽度、展向弯曲和表面扰动在内的三维性如何影响部分淹没推进性能。结合起来，这些目标提供了新的理解自由表面的作用，在部分淹没推进。目标将通过测试同时拍打和垂直离开水面的柔性板来解决。关键变量包括扑翼频率和振幅、垂直速度、板刚度和展弦比。多轴力和扭矩测量将有助于推力和效率的比较。除了基于扑翼运动学的参数化之外，性能趋势将根据表面扰动的大小和速度进行缩放。为了解释性能趋势，高速成像将可视化自由表面动力学（包括空气腔和波的形成，飞溅和扰动的程度），粒子图像测速将用于比较尾流。对于长宽比之间性能不同的情况，将利用推进器形状的3D成像来解释这些观察结果。此外，该项目将有助于容积流量成像的开放获取工具，通过开源项目公开传播材料。该奖项反映了NSF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。