Phosphor thermometry in combustion applications

A new approach for phosphor-based temperature determination is presented. T his method is based on comparison between the spectrally resolved phosphore scent emission and a database of spectra collected at a series of temperatu res. Applications of two phosphor materials, Gd2O2S:Tb and Mg-4(F)GeO6:Mn, possessing different and complementary temperature sensitivities are illust rated. Efficient and accurate comparison is demonstrated between applicatio n and calibration spectra with the use of a custom program featuring a gene ral regression neural net algorithm. With this approach, single laser-pulse , spatially resolved measurements are demonstrated. Applications of the tec hnique reported here include measurements of the surface temperature of a t hermophoretic sampling probe, the surface temperature of a porous burning s olid, wick surface temperatures of supported diffusion flames of acetone, h eptane, and decane, and the cellulose pyrolysis and char oxidation temperat ures associated with flame spread across a thermally thin fuel at 300 and 7 00 Torr air pressure.