ISSN Online: 2377-424X
ISBN CD: 1-56700-226-9
ISBN Online: 1-56700-225-0
International Heat Transfer Conference 13
TEMPERATURE MEASUREMENTS OF BINARY EVAPORATING DROPLETS USING THREE COLOR LASER-INDUCED FLUORESCENCE
要約
The optimization of the combustion process of liquid commercial petroleum requires the fine understanding of multi-component droplet vaporization, especially when each component evaporates at different boiling temperature.
This paper presents the application of a novel technique to the study of the temperature of bi-component droplets along a monodisperse stream. Based on the three-color extension of the two-color laser-induced fluorescence (LIF) technique, mean droplet temperatures can be measured regardless of the composition. The method requires adding a fluorescent organic dye at low concentration to a fuel composed with a mixture of ethyl-alcohol and acetone. The ratio between the fluorescence signals collected on two spectral bands (having different temperature sensitivities) is then a function of the temperature, regardless of laser intensity, time-dependant tracer concentration, and measurement volume. In the case of binary droplets, the fluorescence signal depends on both temperature and composition. To overcome this problem, a third spectral band is used to calculate a second fluorescence signal ratio and separate the influence of composition and temperature, after proper calibration. The approximate overall accuracy is then of ± 1.3 °C. The technique is demonstrated on two experimental arrangements:
This paper presents the application of a novel technique to the study of the temperature of bi-component droplets along a monodisperse stream. Based on the three-color extension of the two-color laser-induced fluorescence (LIF) technique, mean droplet temperatures can be measured regardless of the composition. The method requires adding a fluorescent organic dye at low concentration to a fuel composed with a mixture of ethyl-alcohol and acetone. The ratio between the fluorescence signals collected on two spectral bands (having different temperature sensitivities) is then a function of the temperature, regardless of laser intensity, time-dependant tracer concentration, and measurement volume. In the case of binary droplets, the fluorescence signal depends on both temperature and composition. To overcome this problem, a third spectral band is used to calculate a second fluorescence signal ratio and separate the influence of composition and temperature, after proper calibration. The approximate overall accuracy is then of ± 1.3 °C. The technique is demonstrated on two experimental arrangements:
- overheated droplets injected at ambient temperature: study of the influence of droplet diameter and spacing for different initial compositions on droplet temperature is performed.
- droplets injected in a hot air plume: the study of the influence of the initial composition and droplet diameter is achieved.