Collaborative Research: Aerodynamic-aeroacoustic performance of poroelastic wings inspired by the silent plumage of owls

猫头鹰是一种非同寻常的捕食者，能够抑制它们的噪音，并在攻击猎物/食物时实现静默飞行。猫头鹰的翅膀边缘图案被认为是它们安静飞行的原因。了解猫头鹰机翼上的流动物理可能会导致许多工程设计的噪音降低，如计算机风扇、推进器、商用机身和风力涡轮机。本项目的主要目的是分析一系列与实验测量相结合的分析和数值模型问题，以阐明具有类似于OWL机翼的梯度孔弹性特性的薄流体加载结构的非定常载荷和噪声产生。该项目通过一个互动式的理论-实验计划解决上述技术缺陷，该计划至少在三个方面有所不同：(1)从基本原理出发，构建分析和数值框架，以预测分级孔弹性结构产生的湍流噪声；(2)在没有背景流动噪声的情况下，对孔弹性边的声学标度定律进行实验验证；(3)开发一种滑翔机，以与猫头鹰听到自身噪声的方式一致的方式，在飞行中测量机翼噪声。建模和验证工作旨在将受生物启发的噪声解决方案转变为低速流动中被动空气动力噪声控制的合理范例，并为未来的仿生猫头鹰降噪研究创建一个实验平台。该项目还将包括与达芬奇科学中心(宾夕法尼亚州阿伦敦市)的K-12教育拓展，以及通过利哈伊生物系统动力学暑期研究所(与北安普顿社区学院合作)以及利哈伊和宾夕法尼亚州立大学之间的设计-建造-飞行竞赛来整合本科生研究参与。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Owls are extraordinary predators that are able to suppress their noise and achieve silent flight while attacking prey/food. The wing fringe pattern of owls is believed to contribute to their quiet flight. An understanding of the physics of the flow over owl wings may lead to noise reductions for many engineering designs, such as computer fans, propulsors, commercial airframes, and wind turbines. The principal aim of this project is to analyze a series of analytical and numerical model problems coordinated with experimental measurement to elucidate the unsteady loading and noise generation of thin fluid-loaded structures with graded poroelastic properties comparable to owl wings. This project addresses the above technical shortcomings through an interactive theoretical-experimental program that distinguishes itself in no fewer than three ways: (i) construction of analytical and numerical frameworks to predict turbulence noise generation by graded poroelastic structures, from first principles; (ii) experimental validation of acoustic scaling laws for poroelastic edges, without background flow noise; and (iii) development of a glider to measure wing noise on the fly in a manner consistent with how owls hear their self-noise. The modeling and validation efforts aim to transform a biologically-inspired noise solution into a rational paradigm for passive aerodynamic noise control in low-speed flows and to create an experimental platform for future bionic owl noise-reduction studies. This project will also include K-12 educational outreach with the DaVinci Science Center (Allentown, PA), as well as integrate undergraduate research involvement through the Lehigh Biosystems Dynamics Summer Institute (in partnership with Northampton Community College) and through a design-build-fly competition between Lehigh and Penn State.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.