| Summary: | This paper reports the quantitative method of vapor concentration in unsteady evaporating gasoline type spray with Laser Induced Exciplex Fluorescence（LIEF）. The LIEF is an exciplex fluorescence method developed by Melton to visualize the liquid and vapor phases separately. In this study, iso-octane（92 vol%）, benzene（4 vol%）, and triethylamine（4 vol%） were used as a fluorescent agent that emit excited complex fluorescence that can optically separate fluorescence from the liquid phase and the vapor phase respectively. We tested the dependence of the fluorescence characteristics on the vapor concentration, ambient pressure, and ambient temperature when quantifying the vapor concentration. The relationship between the vapor concentration and the fluorescence intensity ratio was similar to the theoretical relationship. Furthermore, the relationship between the fluorescence intensity ratio and each parameter could be considered as a function of only its parameter. Since the fluorescence intensity is proportional to the laser incident light intensity and the emitted laser light has a Gaussian intensity distribution, the intensity distribution of the laser sheet light could be predicted, and the captured image could be corrected. For quantitative measurement, we used the image analysis method of vapor concentration quantification measurement of direct injection diesel spray developed by Senda et al. The quantitative distribution of vapor concentration was measured by applying the method to the results of simultaneous measurement of Mie scattering, exciplex fluorescence, and monomer fluorescence.
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