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

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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.