CAREER: Resolving Turbulence-Chemistry Interaction Using Novel Laser Diagnostics

Clemson University, Clemson SC

Investigators

Abstract

0844939 Ma Understanding 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.