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.

生物通常在水面具有专门的运动策略。它们的机车解决了独特的限制，包括表面波，溅起和减少空气的力产生，这比水的密度低一千倍。这些行为为水下车辆带来了独特的设计机会，其中包括从水到空中起飞，操纵和近地面站持有的应用。尽管这些生物学实例普遍存在，但仍需要有关生物启发的拍打推进在部分淹没时的性能的新信息。这项工作着重于理解水面对部分淹没推进性能的影响。除了水下车辆之外，这项工作还有助于解释近地表运动和水上运动的生物力学。该项目将在动手研究问题上培训一个本科生的跨学科团队。该项目还将为本科人类学和设计专业的学生以及南加州女子高中生的工程研讨会提供支持的生物启发的设计研讨会。这项工作在部分淹没的生物启发的拍摄过程中，实验研究了自由表面和推进器灵活性之间的作用和相互作用。特定目标是确定：（1）推进性能如何随拍打运动所产生的表面灾难的大小和速度而定。 （2）在部分淹没的拍打运动中，自由表面如何变形，包括柔韧性对观察到的表面行为的影响。 （3）三维（包括有限宽度，跨度弯曲和表面疾病）如何影响部分淹没的推进性能。这些目标结合在一起，对自由表面在部分淹没的推进中的作用提供了新的了解。将通过测试只是同时拍打并垂直从水中出现的柔性板来解决目标。关键变量包括拍打频率和放大器，垂直速度，板刚度和纵横比。多轴力和扭矩测量将有助于比较推力和效率。除了基于拍打运动学的参数外，还将根据表面灾难的大小和速度来缩放性能趋势。为了解释性能趋势，高速成像将可视化自由表面动态（包括空腔和波浪形成，飞溅以及灾难的范围）和粒子图像速度法将用于比较唤醒。对于纵横比之间的性能不同的情况，将利用推进器形状的3D成像来解释这些观察结果。此外，该项目将有助于开放式流动成像的开放式工具，并通过开源项目公开传播材料。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子优点和更广泛的影响标准来评估NSF的法定任务。