Phosphor thermometry and vibrational coherent anti-stokes Raman spectroscopy (CARS) were appliedsimultaneously to examine gas–solid interfaces in a generic combustor. For this purpose, an internally aircooledobstacle was installed within an optically accessible, pressurized combustion chamber. During theoperation of a turbulent, swirled n-heptane flame, the obstacle’s surface temperature and the surface-normalgas temperature distribution were measured. The surface temperature was determined by ThermographicPhosphors, materials whose phosphorescence decay times depend on their temperature.Following a pulsed UV laser excitation (355 nm), the 659 nm emission band of Mg4FGeO6:Mn was monitoredby a photomultiplier tube.Non-invasive temperature measurements in the flue gas region of the n-heptane spray flame near thesurface were performed pointwise by vibrational CARS of diatomic nitrogen. Beams from a frequencydoubled Nd:YAG laser (532 nm) and a modeless broadband dye laser (607 nm) were phase-matched withina surface-parallel, planar BOXCARS configuration. This allowed gas phase thermometry as close as 30 lmto the surface.The thermal boundary layer and wall temperature measurements were consistent with each other. Thisdemonstrates the potential of spectrocopic techniques to study gas–solid interfaces with high temporal andspatial resolution. Using the interior surface temperature within the cooling channel measured by a thermocouple,the heat flux through the wall and the local heat transfer coefficient at the front side of the obstaclewere estimated.
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