CAREER: Modulated Infrared Laser-Induced Fluorescence for Imaging Temperature and Combustion Species in Next-Generation Combustion Systems

许多下一代内燃机(例如，柴油和汽油发动机)将在较低的温度下运行，以提高效率和减少污染物排放。不幸的是，由于各种燃烧现象在较低的温度下会加强，控制这些发动机的燃烧物理并没有得到很好的理解。此外，我们无法监测燃烧过程中形成的气体温度和关键分子物种，这大大限制了我们对这些过程的理解。这项工作的主要目标是通过开发和应用新的激光诊断技术来提高我们对低温燃烧的理解。完成这个项目将提供广泛适用的基于激光的成像诊断技术，能够量化气体温度和关键分子物种。这项工作将产生描述火焰物理和点火的基本数据集，这些条件代表了未来发动机中发现的那些条件。该项目将支持在燃烧、激光光谱学和光学领域工作的众多博士生和更广泛的科学界的研究和教育。这将通过实验研究计划和开发专注于燃烧诊断的新课程和交互式网络工具来实现。许多高效率、低排放发动机的燃烧是通过自动点火和冷热湍流火焰的复杂组合实现的。这些现象以及它们之间的相互作用没有被很好地理解，部分原因是缺乏能够解决低温和高温燃烧区域的温度和物质场的诊断方法。调制红外平面激光诱导荧光(MIR-PLIF)技术将被开发并应用于弥补这一差距，该技术提供对温度以及中间和稳定燃烧产物的高速成像。将开发能够定量预测高温气体中红外荧光产量和振动非平衡的光谱和动力学模型，以实现分子物种的定量成像。MIR-PLIF将被用来确定热力学条件如何改变冷和热湍流火焰的时变结构，以及冷火焰如何影响高温点火。最近开发的燃烧器技术将被利用和扩展，以使这些研究能够在与下一代发动机相关的广泛条件下进行。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Many next-generation combustion engines (e.g., diesel and gasoline engines) will operate at lower temperatures in order to improve efficiency and reduce pollutant emissions. Unfortunately, the combustion physics governing these engines is not well understood due to a variety of combustion phenomena which strengthen at lower temperatures. Further, our understanding of these processes is significantly limited by our inability to monitor the gas temperature and key molecular species formed throughout the combustion process. The primary goal of this work is to improve our understanding of combustion initiated at lower temperatures through the development and application of new laser diagnostics. Completing this project will provide broadly applicable laser-based imaging diagnostics capable of quantifying gas temperature and key molecular species. This work will produce fundamental datasets describing flame physics and ignition at conditions representative of those found in future engines. This project will support the research and education of numerous doctoral students and the greater scientific community working in the fields of combustion, laser spectroscopy, and optics. This will be achieved through the experimental research program and the development of a new course and interactive web-based tools focused on combustion diagnostics.Combustion in many high-efficiency, low-emissions engines is achieved through a complex combination of autoignition and both cool and hot turbulent flames. These phenomena and the interaction between them are not well understood, in part, due to the lack of diagnostics which can resolve the temperature and species fields across both the low- and high-temperature combustion regimes. Modulated infrared planar laser-induced fluorescence (MIR-PLIF) techniques providing high-speed imaging of temperature and both intermediate and stable combustion products will be developed and applied to bridge this gap. Spectroscopic and kinetic models, capable of quantitatively predicting infrared fluorescence yields and vibrational non-equilibrium in high-temperature gases, will be developed to enable quantitative imaging of molecular species. MIR-PLIF will be used to determine how thermodynamic conditions alter the time-varying structure of both cool and hot turbulent flames, and how cool flames influence high-temperature ignition. Recently developed burner technologies will be utilized and expanded to enable these studies to be conducted across a wide range of conditions that are relevant to next-generation engines.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.