International Research Fellowship Program: Aeroacoustic Model for an Elastic Lifting Surface with a Soft, Sound Absorbant Coating: The Silent Flight of Owls

0965248 Jaworski国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。 该计划的奖项提供了联合研究的机会，以及使用独特或互补的设施，专业知识和国外的实验条件。这个奖项将支持一个二十四-一个月的研究奖学金由贾斯汀Jaworski博士与博士工作.奈杰尔皮克和蒂莫西J.佩德利在剑桥大学在英国.猫头鹰采用多种噪声抑制功能，以减少其听觉灵敏度内的声学签名，它们的猎物，其中大部分是由人类听觉共享的。 这些噪声抑制特征中的两个，位于机翼的某些区域的柔软的纤维天鹅绒材料和弹性的锯齿状后缘，被认为协同工作以减少背景湍流对噪声散射的影响并在大的频率带宽内消散声音。 尽管最近的努力量化的气动声学效应的软涂层实验，一个可行的理论模型目前还不存在。 目前的研究系统地解决了这些噪声抑制机制的气动声学影响，并隔离多孔介质声学的影响，从气流场上的天鹅绒涂层的空气动力学影响。 通过这种方式，可以将拟议研究的结果直接与实验和最先进的航空声学计算进行比较。 每个猫头鹰噪声抑制机制减少到物理上一致的模型，扩展分析气动声学研究文献中的结果，最终在一个广义和统一的空气动力学和气动声学框架的一种新的计算设计工具。 从这项工作中开发的设计工具和原则将使未来的固定翼和扑翼微型飞行器（MAV）的设计更加安静，这些飞行器在类似于猫头鹰的流动状态下运行。 从这项研究中获得的经验教训也可以为在较高雷诺数和马赫数下的升力面降噪技术提供信息，包括功能性静音飞行器。

0965248JaworskiThe International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad.This award will support a twenty-four-month research fellowship by Dr. Justin Jaworski to work with Drs. Nigel Peake and Timothy J. Pedley at the University of Cambridge in the UK.Owls employ multiple noise suppression features to reduce their acoustic signature within the hearing sensitivity of their prey, much of which is shared by human audition. Two of these noise suppression features, a soft, fibrous velvet material located at certain areas of a wing and an elastic, serrated trailing edge, are thought to work in concert to reduce the effect of background turbulence on noise scattering and to dissipate sound within a large frequency bandwidth. Despite recent efforts to quantify the aeroacoustic effect of a soft coating experimentally, a viable theoretical model does not currently exist. The present research systematically addresses the aeroacoustic impact of these noise suppression mechanisms and isolates the impact of porous media acoustics from the aerodynamic influence of the velvet coating on the flow field. In this manner, the results from the proposed research can be compared directly against experiment and state-of-the-art aeroacoustic computations. Each of the owl noise suppression mechanisms is reduced to physically consistent models that extend analytical aeroacoustics results in the research literature, culminating in a generalized and unified aerodynamic and aeroacoustic framework for a novel computational design tool. The design tool and principles developed from this work will enable quieter future designs for fixed and flapping wing micro air vehicles (MAVs) that operate in flow regimes similar to owls. Lessons learned from this research may also inform sound reduction techniques for lifting surfaces at higher Reynolds and Mach numbers including functionally-silent air vehicles.