CAREER: Flow distortions of quiet serrated structures

声学噪声是空气动力学结构附近流动不可避免的副产品，噪声通过与固体的湍流相互作用而被放大。流传噪声会影响环境噪声水平，而环境噪声水平是国家和国际飞机噪声法规的目标。然而，噪声也限制了风力涡轮机、新兴的商用无人机以及高效城市航空旅行的新范例的商业足迹。为了解决这一挑战，工程实践中采用了锯齿形边缘设计，这既会影响噪声水平，也会影响流体动力学。基于其流动物理的对锯齿的声学理解仍然不发达，主流噪声理论不能可靠地预测噪声水平的变化。这个项目的主要目的是建立新的理论模型来研究边缘锯齿如何影响其局部流体流动及其声学特征。所提出的理论研究计划的目标是：(1)通过噪声实验的数据减少了解锯齿如何扭曲来流湍流；(2)模拟和预测与前缘和后缘相关的流动的扭曲；以及(3)计算扭曲的锯齿对局部非定常压力和辐射噪声的影响。综合研究和教育计划旨在为锯齿噪声的产生提供一个预测性的理论框架，该框架将与全球研究伙伴协调进行实验和数值验证，并将为研究生提供国际研究交流机会。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)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。

Acoustic noise is an unavoidable byproduct of flows near aerodynamic structures, where noise is amplified by turbulence interactions with solid bodies. Flow-borne sound contributes to environmental noise levels that are targets for national and international aircraft noise regulations. However, noise also constrains the commercial footprints of wind turbines, emergent commercial unmanned air vehicles, and new paradigms for efficient urban air travel. To address this challenge, serrated edge designs have been adopted in engineering practice, which can affect both the noise level and the fluid dynamics. An acoustic understanding of serrations based on their flow physics remains underdeveloped, where the prevailing noise theory cannot reliably predict changes in noise level. The principal aim of this project is to develop new theoretical models for how edge serrations affect their local fluid flow and their acoustic signature.The objectives of the proposed theoretical research program are to: (1) understand via data reduction of noise experiments how serrations distort incoming flow turbulence; (2) model and predict the distortion of flows pertinent to leading edges and trailing edges; and (3) compute the effect of distorted serrations on local unsteady pressures and the radiated noise. The integrated research and education plan aims to furnish a predictive theoretical framework for serration noise generation, which will be coordinated with global research partners for experimental and numerical validation and will provide international research exchange opportunities for graduate students. 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).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.