Phosphor thermometry in combustion applications

A new approach for phosphor-based temperature determination is presented. This method is based on comparison between the spectrally resolved phosphorescent emission and a database of spectra collected at a series of temperatures. Applications of two phosphor materials, Gd₂O₂S:Tb and Mg₄(F)GeO₆:Mn, possessing different and complementary temperature sensitivities are illustrated. Efficient and accurate comparison is demonstrated between application and calibration spectra with the use of a custom program featuring a general regression neural net algorithm. With this approach, single laser-pulse, spatially resolved measurements are demonstrated. Applications of the technique reported here include measurements of the surface temperature of a thermophoretic sampling probe, the surface temperature of a porous burning solid, wick surface temperatures of supported diffusion flames of acetone, heptane, and decane, and the cellulose pyrolysis and char oxidation temperatures associated with flame spread across a thermally thin fuel at 300 and 700 Torr air pressure.