Characterization of wall temperature distributions in a gas turbine model combustor measured by 2D phosphor thermometry

Abstract

Instantaneous 2D phosphor thermometry was performed on the windows and combustion chamber posts of an optically accessible dual-swirl gas turbine model combustor operated with CH4 at atmospheric pressure. Two phosphors were used in order to measure different surface temperature ranges: YAP:Eu (temperature range 850 K – 1150 K) and YAG:Eu (temperature range 1100 K – 1300 K). Phosphor coatings were applied to the combustion chamber post and to three vertically oriented stripes on one combustion chamber window. Using interpolation, this allowed the determination of the surface temperature of the complete combustion chamber window. Heat losses across the combustion chamber window were determined by measuring the surface temperature on the inner and outer surface of the window. The phosphor coating was illuminated using the fourth harmonic of a Nd:YAG laser, which was formed into a broad light sheet. The spatially resolved, temperature-dependent decay rate of the phosphorescence was measured with a high speed CMOS camera. Three flames with similar flow fields and thermal powers between 22.5 kW and 30 kW and equivalence ratios between 0.63 and 0.83 were studied. Because the flame characteristics including flow field, heat release and temperature distributions were known from previous measurements the interaction between the flame and the surface temperature could be examined. In this way, the different wall temperatures of the flames could be explained.