RII Track-4: Exploiting Thermoacoustic Assonance to Enrich Multifunctional Meta-Structures

在一些工程应用中，特别是在航空航天领域，空气噪声减轻是一个重大挑战，空气噪声降低效率，阻碍隐身，造成环境污染，并削减商业可行性。传统技术在解决空气噪声方面已经达到了实际极限，特别是对于低频（~1000 Hz）频谱。与NASA的兰利研究中心合作，热声元结构（TAMS），将探索一类新的多功能结构，重点是减轻飞机涡轮风扇发动机的核心噪声。一个创新的多物理机制融合在一个新的设计框架，称为“assonance”将被调查，以丰富宽带，低频性能的TAMS。预计新的见解将获得潜在的现象，使建模工具的开发，以创建原型TAMS在美国宇航局的设施进行评估。该项目的成功完成将提供一种新的机载噪声缓解技术，提高几个军事和商业工程应用的关键使命能力。该项目与俄克拉荷马州的区域工业和教育生态系统的经济愿景和优势有着实质性的一致性，同时也有助于国家航空航天和国防利益，并直接为全球可持续航空提供技术解决方案。该项目的总体目标是对热声元结构（TAMS）的标度律和结构-性能关系提出新的见解。有助于为多功能应用开发有效的解决方案，特别是在航空航天领域。具体而言，将探讨解决美国航天局飞机涡轮风扇发动机核心噪音缓解优先事项的机会。核心噪声具有显著的低频（~1000 Hz）分量，这是使用常规声学衬垫尚未解决的。利用发动机芯壁上的热梯度，将采用结构材料及其交互式多物理机制的创新设计的汇合，将热声元件嵌入衬垫元结构中。一个新的，计算效率高的建模工具的基础上的多物理模型TAMS嵌入Rott的模型，热声与美国宇航局的Zwikker-Kosten传输线（ZKTL）模型的声学内衬内的振声元件结合提出开发。一个新兴的超材料启发的设计框架，称为“assonance”将被探索，以丰富TAMS的宽带性能。在与NASA的合作中，将利用最先进的结构材料配置和制造工艺来构建原型测试件，以使用NASA的实验设施进行评估。在不同的声学条件下生成大量的数据集将有助于验证模型，提取功率体积比的比例律，辐射阻抗和频率-热梯度依赖性的影响，并建立新的见解到结构-性能关系的assonant元结构。该项目的成功完成将提供一种新的空气噪声缓解技术，增强在几个军事和商业工程应用中的关键使命能力，并直接为可持续的全球航空做出贡献。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。

Airborne noise mitigation is a significant challenge in several engineering applications, particularly in the aerospace realm where it diminishes efficiency, hampers stealth, contributes to environmental pollution and curtails commercial viability. Conventional technologies have reached practical limits in addressing airborne noise, especially for low-frequency (~1000 Hz) spectra. In partnership with NASA’s Langley Research Center, Thermo-Acoustic Meta-Structures (TAMS), a new class of multifunctional structures will be explored with a focus on mitigating aircraft turbofan engine’s core-noise. A confluence of innovative multi-physical mechanisms within a novel design framework termed ‘assonance’ will be investigated to enrich broadband, low-frequency performance for TAMS. It is expected that new insights will be gained into underlying phenomena enabling the development of modeling tools to create prototype TAMS for evaluation in NASA’s facilities. Successful completion of this project will deliver a new technology for airborne noise mitigation, enhancing critical mission capabilities in several military and commercial engineering applications. This project has substantial congruence with the economic vision and strengths of the regional industrial and educational ecosystem of the State of Oklahoma while also contributing to national aerospace and defense interests and directly enabling technological solutions for sustainable global aviation.The overarching goal of this project is to educe new insights into scaling laws and structure-performance relationships for Thermo-Acoustic Meta-Structures (TAMS) aiding the development of impactful solutions for multifunctional applications, especially in the aerospace realm. Specifically, opportunities to address the aircraft turbofan engine core-noise mitigation priorities of NASA will be explored. Core-noise has significant low-frequency (~1000 Hz) components, as yet unaddressed using conventional acoustic liners. Utilizing available thermal gradients across the engine’s core-wall, a confluence of innovative designs for structural materials and interactive multiphysical mechanisms thereof will be employed to embed thermoacoustic elements into liner meta-structures. A new, computationally-efficient modeling tool based on a mulitphysical model for TAMS embedding the Rott’s model for thermoacoustics in conjunction with vibroacoustic elements within NASA’s Zwikker-Kosten Transmission Line (ZKTL) model for acoustic liners is proposed to be developed. An emergent metamaterials-inspired design framework termed ‘assonance’ will be explored to enrich broadband performance for TAMS. In partnership with NASA, state-of-the-art structural material configurations and fabrication processes will be utilized to construct prototypical test articles for evaluation using NASA’s experimental facilities. Generation of extensive data sets under varying acoustic conditions will help validate the model, extract scaling laws for power-to-volume ratio, influence of radiation impedance and frequency-thermal gradient dependencies and establish new insights into structure-performance relationships for assonant meta-structures. Successful completion of this project will deliver a new technology for airborne noise mitigation, enhancing critical mission capabilities in several military and commercial engineering applications and directly contributing to sustainable global aviation.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.