<title>Nonintrusive laser-induced imaging for speciation and patternation in high-pressure gas turbine combustors</title>

The next generation of ga turbine combustors for aerospace applications will be required to meet increasingly stringent constraints on fuel efficiency, noise abatement, and emissions. The power plants being designed to meet these constraints will operate at extreme conditions of temperature and pressure, thereby generating unique challenges to the previously employed diagnostic methodologies. Current efforts at NASA Glenn Research Center GRC utilize optically accessible, high-pressure flametubes and sector combustor rigs to probe, via advanced nonintrusive laser techniques, the complex flowfields encountered in advanced combustor designs. The fuel-air mixing process is of particular concern for lowering NOx emissions generated in lean, premixed engine concepts. Using planar laser-induced fluorescence we have obtained real- time, detailed imaging of the fuel spray distribution for a number of fuel injectors over a wide range of operational conditions that closely match those expected in the proposed propulsion systems. Using a novel combination of planar imaging of fuel fluorescence and computational analysis that allows an examination of the flowfield from any perspective, we have produced spatially and temporally resolved fuel-air distribution maps. These maps provide detailed insight into the fuel injection process at actual conditions never before possible, thereby greatly enhancing the evaluation of fuel injector performance and combustion phenomena.