Investigation of NO Formation and Transport in Combustion Systems using Planar Laser Induced Fluorescence

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The ability to accurately predict the formation and transport of nitric oxide (NOx) in practical combustion systems, such as gas turbines, is a necessary step to reduce the harmful emission of this toxic gas into the environment. Negative environmental consequences of NOx emission include ozone depletion, global warming, smog formation, and respiratory illnesses. With recent advances in computing power, it is possible to mitigate this problem by using computational fluid dynamics (CFD) algorithms with state-of-the-art combustion and turbulence models as an optimization design tool. This approach relies on a model validation process in which CFD predictions are compared against experimental data sets. In high pressure combustion environments, planar laser induced fluorescence (PLIF) is an ideal non-intrusive, experimental technique to both visualize qualitative distributions of NOx and to extract quantitative data such as gas velocity, temperature, pressure, and species concentrations. However, the application of NO PLIF techniques to high pressure combustion flows is difficult due to the interference of the molecular oxygen PLIF signal and laser attenuation from UV light absorption. The main research object is to understand NOx formation and transport in the context of fuel staging strategies used in gas turbine engines to reduce NOx emissions. With the development of a dual-driver shock tube facility, an NO PLIF system will initially be used to study the formation of NO at high temperatures and mixing of an NO seeded fuel jet into a crossflow. Quantitative PLIF techniques such as Doppler shift velocimetry, molecular tagging velocimetry, and two-line thermometry will be developed. Modeling of the PLIF signal equation will be undertaken to produce computational flow images. This will allow direct comparisons between the experimental and numerical PLIF images needed for model validation. Validated combustion models will be used as investigative tools to study current low-NOx fuel-staging strategies used in gas turbine combustors.