Exciplex Method for Remote Probing of Fuel Droplet Temperature : Effects of Ambient Conditions on Fluorescence

Abstract

An exciplex-based fluorescence method was employed for remote, nonintrusive, instantaneous thermometry of a fuel droplet evaporating or burning in a stream of gaseous mixture. The fluorescence emission spectra from a droplet doped with naphthalene and N, N, N', N'-tetramethyl-p-phenylenediamine(TMPD)were measured with an optical multichannel analyzer. The effects of several parameters including the composition of the ambient gas and the concentrations of the dopants on the fluorescence emission spectra were studied. The results showed that the oxygen in the ambient gas was a major quencher for the fluorescence and that the fluorescence emission spectra varied with the concentration of naphthalene and TMPD. The velocity of the ambient gas had no appreciable effect on the fluorescence emission spectra. It was suggested that the temperature dependence of the ratio of fluorescence intensities at two different wavelengths for a droplet burning in air was the same as that for a droplet evaporating in nitrogen.