CAREER: Resolving Turbulence-Chemistry Interaction Using Novel Laser Diagnostics

0844939Ma 理解湍流是物理科学的巨大挑战之一；理解湍流和化学的复杂相互作用在科学上更具挑战性，但它在工程设备和过程中也无处不在。对湍流化学相互作用（TCI）的深入了解可以从根本上改进此类设备和工艺，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，可以将基础物理解析到一个新的水平。该项目提出了新的实验技术来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）创建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。将前体分子接种到感兴趣的气态或两相流中，然后通过激光脉冲光解离。由于解离速度为纳秒级，因此可以捕获流动视图，并且可以暂时解析 TCI。因为解离是完全的，所以所得的照片片段代表了种子前体的分布。对这种光碎片的浓度进行成像可以生成关键流动参数的多维测量，例如混合分数、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。该项目试图开发基于PD的两相流统一诊断，即该诊断基于相同的示踪剂和传感技术（甚至相同的激光器和相机）来表征两相流，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。这个具有挑战性的项目的成功将在技术上产生重大影响，但它也有可能通过融入一系列教育活动而在教育上产生重大影响。该项目的最终目标是通过协作、传播数据以及在课堂和实验室教授其概念来开发这些技术以供广泛使用。实验研究将有助于改革传统的基于讲座的课程，利用物理和虚拟实验室提供交互式学习机会，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.