Two-dimensional gas-phase temperature measurements using fluorescence lifetime imaging

Two-dimensional (2D) temperature images of turbulent hot nitrogen hows have been obtained by use of a novel technique involving fluorescence lifetime imaging. Nitrogen flows were doped with naphthalene vapor. The fluorescence lifetime of naphthalene decreases from 180 ns at 25 degrees C to 35 ns at 450 degrees C, and this temperature dependence ran be used to calculate the temperature from the fluorescence lifetime in oxygen-free environments. With the current apparatus and with naphthalene as the fluorescent dopant, the error in the absolute temperature was estimated to be +/-15 degrees C in the range of 25 to 450 degrees C. This application demonstrates that fluorescence lifetime imaging, which does not depend on the absolute concentration on the fluorescent dopant, may be useful in a variety of turbulence, temperature, and other combustion-related studies.