Flame monitoring of a model swirl injector using 1D tunable diode laser absorption spectroscopy tomography

Distributions of temperature and H₂O concentration in a swirling flame are critical to evaluate the performance of a gas turbine combustor. In this paper, 1D tunable diode laser absorption spectroscopy tomography (1D-TDLAST) was introduced to monitor swirling flames generated from a model swirl injector by simultaneously reconstructing the rotationally symmetric distributions of temperature and H₂O concentration. The optical system was sufficiently simplified by introducing only one fan-beam illumination and a linear detector array of 12 equally-spaced photodetectors. The fan-beam illumination penetrated a cross section of interest in the swirling flame and the transmitted intensities were detected by the detector array. With the transmitted intensities in hand, projections were extracted and employed by a 1D tomographic algorithm to reconstruct the distributions of temperature and H₂O concentration. The route of the precessing vortex core generated in the swirling flame can be easily inferred from the reconstructed profiles of temperature and H₂O concentration at different heights above the nozzle of the swirl injector.