Measurement of the temperature distribution within monodisperse combusting droplets in linear streams using two-color laser-induced fluorescence

Two-color laser-induced fluorescence can be use to perform space-averaged flying droplet temperature measurements. In this paper, the possibility to extend this technique to the measurement of the temperature distribution within a moving combusting droplet is considered and demonstrated. This technique may provide new experimental data related to the heat diffusion in liquid fuel droplets injected in high-temperature gas streams, for example, in combustion chambers. The main principles of the technique and the data reduction process are discussed, and a test on combusting a monodisperse ethanol droplets (200 m in diameter) stream is presented.Nomenclature a _i , b _i temperature sensitivity coefficients for i th spectral band - C molecular concentration of fluorescent tracer - D droplet diameter - I ₀ incident laser beam intensity - I _f fluorescence intensity - K _opt optical constant - K _spec spectroscopic constant - V _c collection volume - R _f fluorescence ratio - T absolute temperature - T _i injection temperature - V _i injection velocity - ( x, y , z) spatial coordinates Greek symbols temperature sensitivity coefficient