CAREER: Resolving Turbulence-Chemistry Interaction Using Novel Laser Diagnostics

理解湍流是物理科学的重大挑战之一；理解湍流和化学的复杂相互作用在科学上甚至更具挑战性，但它也普遍存在于工程设备和过程中。对湍流-化学相互作用(TCI)的正确理解可以导致此类装置和过程的根本改进，有助于解决能源安全和全球变暖等社会问题。掌握它需要创新的方法，能够将潜在的物理问题解决到一个新的水平。这个项目提出了新的实验技术，以解决基础和应用系统中的科学和应用问题。其概念是通过使用光解离(PD)产生可以光学测量的光碎片来表征湍流和化学，特别是在两相流中。前体分子被播种在感兴趣的气相或两相流中，然后被激光脉冲光解。由于解离的速度是纳秒的，所以可以捕捉到流动的图像，并且可以在时间上解析TCI。因为解离是完全的，所以产生的光碎片代表了种子前体的分布。成像这种光碎片的浓度可以产生关键流动参数的多维测量，如混合物分数、标量耗散率和反应速率，这些参数对TCI至关重要，但通常无法用现有的实验方法测量。本项目试图开发一种基于PD的两相流统一诊断方法，即基于相同的示踪剂和传感技术(甚至是相同的激光和照相机)来描述两相流的特征，以阐明两相流中丰富的相互作用。将建立广泛的合作来分享和传播实验结果。这一具有挑战性的项目的成功将在技术上产生重大影响，但它也有可能通过整合到一系列教育活动中在教育方面产生重大影响。该项目的最终目标是通过合作、传播数据并在课堂和实验室教授概念，开发出广泛使用的这些技术。这项实验研究将有助于改革传统的讲授课程，使用物理和虚拟实验室提供互动学习机会，这些机会也可以扩展到大学课堂之外。

0844939MaUnderstanding turbulence is one of the great challenges of physical science; understanding the complicated interactions of turbulence and chemistry is scientifically even more challenging, but it is also ubiquitous in engineering devices and processes. A sound understanding of turbulence-chemistry interaction (TCI) can lead to fundamental improvements in such devices and processes, contributing to the solution of societal issues such as energy security and global warming. Mastering it calls for innovative methods that can resolve the underlying physics to a new level. This project proposes new experimental techniques to address both the science and applications in fundamental and applied systems.The concept is to characterize both the turbulence and the chemistry, especially in two-phase flows, by using photodissociation (PD) to create photofragments that can be measured optically. Precursor molecules are seeded in the gaseous or two-phase flow of interest, then photodissociated by a laser pulse. Because of the nanosecond rapidity of the dissociation, a view of the flow is captured and the TCI can be temporally resolved. Because the dissociation is complete, the resulting photofragment represents the distribution of the seeded precursor. Imaging the concentration of this photofragment can then generate multidimensional measurements of key flow parameters like mixture fraction, scalar dissipation rate, and rates of reaction, which are critical to TCI but generally not measurable with existing experimental methods. This project attempts to develop a unified diagnostic for two-phase flows based on PD, in the sense that the diagnostic characterizes both phases based on the same tracer and sensing technique (even the same lasers and cameras) to elucidate the rich interactions in two-phase flows. Extensive collaborations will be established to share and disseminate the experimental results.Success in this challenging project will have significant impact technologically, but it also has the potential for a significant impact educationally through integration into a range of educational activities. The ultimate aim of this project is to develop these techniques for wide use through collaboration, disseminating data, and teaching its concepts in the classroom and the laboratory. The experimental research will be useful in reforming traditional lecture-based courses, using physical and virtual laboratories to deliver interactive learning opportunities that can also be extended beyond college classrooms.