Understanding and developing new noise reduction mechanisms for aerofoils in unsteady flow through the use of analytical mathematics

该项目的核心是为复杂的流固耦合问题找到数学解决方案，将各种先进的数学技术结合在一起，以解决航空航天行业的关键问题，如降低飞机噪音。来自机场和风电场的过量环境噪声是影响公众健康以及航空和可持续能源产业扩张的关键问题。目前，空气声学研究的一个不断扩大的领域是对飞机或风力涡轮机标准叶片的前沿(前端)和后端(后端)的改装。据信，这些适应可以显著减少产生的噪音，并在很大程度上受到大自然的启发，特别是猫头鹰安静的飞行。众所周知，猫头鹰在鸟类中是独一无二的，因为它们几乎无声地飞行。这被认为是可能的，因为它们的翅膀拥有许多其他物种所没有的特征。通过创造新的设计，旨在模仿这些猫头鹰般的特征，该项目将试图显著减少飞机和风力涡轮机叶片产生的噪音。航空发动机叶片产生的噪音的一个主要来源是前缘噪音，由非稳定流体与固体前面的相互作用产生。相反，后缘噪声是机身和风力涡轮机噪声的主要贡献者，这些噪声是由于叶片上方的湍流与叶片后部(后缘)的相互作用而产生的。了解和量化产生这些不同类型噪声的机制对于了解可以对当前设计进行哪些调整以减少这些系统发出的总体噪声至关重要。潜在的降噪设计包括：锯齿形叶片，或多孔灵活的后缘，或流苏前缘。对这些设计的有效性的研究通常是实验性的或数值的，不能更深入地研究结果来告诉你为什么这样的设计有效，无论它是不是有效。这个项目的最终目的是提供原因的答案。使用解析方法得出的数学解可能非常强大，因为它们保留了这些流-结构相互作用问题的重要物理原理，但显著降低了计算成本，并可以解决数值模型难以解决的情况，例如高频噪声的产生。数学预测的速度可以确定需要进一步研究的重要领域，为开发新的降噪或提高性能的技术提供了先机。通过数学分析，该项目将深入了解这些经过调整的前缘和后缘设计降低噪音的机制，并获得关键设计特征之间的关系，例如后缘适应或原始叶片几何形状的孔隙率，以及总体降噪，从而允许快速优化设计，而不需要大量实验或昂贵的计算。

This project centres on finding mathematical solutions to complicated fluid-structure interaction problems, bringing together a variety of advanced mathematical techniques to solve key problems in the aerospace industry, such as reducing aircraft noise. Excessive environmental noise from airports and wind farms is a key issue affecting both public health and the expansion of the aviation and sustainable energy industries.A current expanding area of research in aeroacoustics is in leading-edge (at the front) and trailing-edge (at the rear) adaptations to standard blades on aeroplanes or wind turbines. It is believed that these adaptations can lead to significant decreases in generated noise and are largely inspired by nature, in particular the silent flight of owls. It is well known that owls are unique among birds in that they fly almost silently. This is believed to be possible due to a number of features their wings possess which are not present in other species. By creating new designs aimed at mimicking these owl-like features, this project shall attempt to significantly reduce noise generated by aircraft and wind turbine blades.A primary source of noise generated by aeroengine blades is leading-edge noise, arising from the interaction of an unsteady fluid with the front of the solid body. Conversely, trailing-edge noise is a dominant contributor to airframe and wind turbine noise, arising due to the interaction of turbulence above the blades with the rear of the blade (the trailing edge).Understanding and quantifying the mechanisms generating these different types of noise is vital to knowing what adaptations can be made to current designs in order to reduce the overall sound emitted by these systems. Potential noise reduction designs include; blades with serrated, or porous and flexible trailing edges, or fringed leading edges. Research into the effectiveness of these designs is typically experimental or numerical, which cannot delve deeper in to the results to tell you why such a design is effective, merely if it is or not. This project ultimately aims to provide the answer to why. Mathematical solutions derived using analytic methods can be incredibly powerful as they preserve the vital physics of these fluid-structure interaction problems, but significantly reduce computational costs and can address cases in which numerical models struggle, such as generation of high-frequency noise. The speed of mathematical predictions can identify important areas that require further investigation, giving a head start to developing new noise-reducing or increased-performance technologies.Through mathematical analysis, this project will give insight into the mechanisms by which these adapted leading- and trailing-edge designs reduce noise, and obtain relationships between key design features, such as the porosity of a trailing-edge adaptation or original blade geometry, and the total noise reduction, allowing for quick optimisation of the design without the need for large numbers of experiments or costly computation.