Two-Dimensional Gas-Phase Temperature Measurements Using Fluorescence Lifetime Imaging

Two-dimensional (2D) temperature images of turbulent hot nitrogen flows 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 °C to 35 ns at 450 °C, and this temperature dependence can 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 °C in the range of 25 to 450 °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.