CAREER: Fundamental Analysis and Computational Modeling of Acoustic Radiation in Turbulent Reacting Flows

该奖项由2009年《美国复苏和再投资法案》(公法111-5)资助。这项研究旨在通过研究湍流反应流和开发计算模型，获得对喷气式飞机噪声污染控制的新的、有用的见解。高旁路涡扇发动机显著降低了喷气噪声，使燃烧噪声成为主要的噪声贡献者。此外，新的清洁燃烧技术产生了增加燃烧噪音的不良影响。预测建模能力之所以不可用，主要是因为对这些现象的科学理解有限，这迫使在地面上实施昂贵的被动消声计划。我们将结合基础分析、NSF TeraGrid系统预测建模能力的开发和实验验证来寻求对这种声辐射的基本理解。将对湍流预混、部分预混和扩散火焰进行基准火焰构型的直接数值模拟，以识别和了解控制声辐射的过程。利用这些知识，将开发出一致的建模能力，适用于燃烧LES中可靠的噪声预测。该模型将在复杂火焰构型的模拟中得到验证，这些火焰构型的实验数据是可用的。这种详细的模拟数据对于识别声源、理解声-热化学耦合机制、表征声-折射效应以及指导实验仪器将是有价值的。在这项研究中开发的模型功能还可以集成到模拟工具中，用于设计飞机发动机、燃气轮机和其他应用中的先进燃烧系统。这种对噪声机制的更好理解也可能对发电领域以外的领域具有潜在的相关性，例如处理太阳声振荡的声学传感和日震应用。一个全面的教育和推广计划是这项职业资助的一部分。它特别强调的是从当地机场附近直接受到飞机噪音污染影响的社区招收代表不足的高中生。通过暑期实习以及通过课堂项目与本科生就解决他们可能涉及的各种噪音和空气污染方面的具体问题进行密切互动，这些高中生将被鼓励从事工程职业，致力于对他们的社区有直接好处的问题。教育计划的另一个组成部分是通过研究活动、暑期学校和本科课程，让一群积极和多样化的本科生接触计算建模和高性能计算。随着越来越多地使用计算建模来解决我们世界的技术挑战，在他们职业生涯早期获得这些技能变得越来越重要。

0844587IhmeThis award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).This research is intended to achieve new, useful insights into control of noise pollution from jet aircraft by studying turbulent reactive flows and developing computational models. Remarkable reductions in jet noise have been achieved with high-bypass turbofan engines, which made combustion noise a leading noise contributor. Furthermore, new clean-combustion technologies have had the unwanted effect of increasing combustion noise. Predictive modeling capabilities are not available largely because of the limited scientific understanding of these phenomena, which forces the implementation of costly passive sound-mitigating programs on the ground.Fundamental understanding of this acoustic radiation will be sought by combining fundamental analysis, development of predictive modeling capabilities on the NSF TeraGrid system, and experimental validation. Direct numerical simulations of benchmark flame configurations will be conducted on turbulent premixed, partially premixed, and diffusion flames to identify and understand the processes controlling acoustic radiation. Using this knowledge, a consistent modeling capability will be developed applicable for reliable noise predictions in combustion LES. This model will be validated in simulations of complex flame configurations for which experimental data are available. Such detailed simulation data will be valuable in identifying acoustic sources, understanding acoustic-thermochemical coupling mechanisms, characterizing sound-refraction effects, and guiding experimental instrumentation. Model capabilities developed in this research can also be integrated into simulation tools for designing advanced combustion systems in aircraft engines, gas turbines, and other applications. This improved understanding of noise mechanism could also be of potential relevance to areas outside the power generation field, such as acoustic sensing and helioseismic applications that deal with solar-acoustic oscillations.A comprehensive education and outreach program is part of this CAREER grant. Its particular emphasis is to recruit underrepresented high-school students from communities in proximity to local airports that are directly affected by aircraft noise pollution. Through summer internships and the close interaction with undergraduate students through classroom projects on specific problems addressing various noise and air pollution aspects they can relate to, these high school students will be encouraged to pursue engineering careers to work on issues that have a direct benefit to their community. Another component of the education plan is to expose a group of motivated and diverse undergraduate students to computational modeling and high-performance computing through research activities, summer schools, and undergraduate curricula. Acquiring such skills early in their careers is increasingly important with the growing use of computational modeling to solve the technological challenges of our world.