Thin Filament Pyrometry (TFP) has been proven to be a useful approach to measure hot gas temperature. The TFP technique involves suspending a thin filament (typically a SiC fiber) in hot gas flow path and calculating the gas temperature from the measured thermal radiance of the filament. Comparing to most optical and laser based non-intrusive techniques, the TFP approach offers significant simplicity, reduced cost and relative ease of applicability, especially at high-pressure gas-turbine type conditions.
In this study, TFP was employed to measure combustor exit gas temperature distributions in an atmospheric combustion rig simulating a model aero-engine combustor burning Jet-A fuel. Hot gas from the combustor was accelerated through a converging nozzle to achieve high exit velocities. The thermal radiation signal from the glowing fiber was collected by a Near Infrared (NIR) camera outfitted with a band pass filter. The gas temperature profile was calculated by an intensity ratio technique. Two-Dimensional temperature maps were obtained via spatially and temporally scanning the TFP system. Temperature measurements at the combustor exit are reported for various fuel-air ratios at Mach numbers around 0.38. A type-B thermocouple stationed at the centerline of the combustor exit was corrected for radiation effects and used to infer the flame temperature for TFP measurement.
The major contributions of the current study to the advancement of the TFP technique for measuring hot gas temperatures are: (1) To the authors’ knowledge, this is the first time that the TFP technique has been used in a liquid fueled combustion system, and (2) The data presented herein were obtained at greater Mach numbers than all previous studies (Ma = 0.38).