Quantitative analysis of vapor concentration in unsteady evaporating gasoline spray with LIEF method (2nd Report：Analysis of mixture-liquid two-phase characteristics)

Abstract

This paper reports the quantitative analysis of vapor concentration in the mixture-liquid two-phase region with Laser Induced Exciplex Fluorescence（LIEF）for the unsteady evaporating gasoline type spray. These methods were used to analyze the mixture-liquid two-phase characteristics in the process of mixture formation. The exciplex fluorescence method, developed by Melton, is a method to optically separate the fluorescence of the liquid and vapor phases, but quantitative analysis of vapor concentration in the mixture-liquid two-phase e region is difficult due to fluorescence cross talk. In this study, the quantitative analysis of vapor concentrations using the average temperature of mixing was used to quantify the vapor concentrations in the mixture-liquid two-phase region by image processing that considers the fluorescence cross talk between the liquid and vapor phases. As a result, the vapor concentration, the temperature of the mixture, and the concentration distribution of the liquid phase in the mixture-liquid two-phase region of the spray cross section were obtained. Based on these results, the correlation diagram between vapor concentration and fluorescence intensity of the liquid phase and the relative frequency distribution of vapor concentration were calculated. A comparison was made between the characteristic values of the fuel and the temperature under the experimental conditions. It was found that the spray consisted mainly of a region where the liquid phase was almost absent and dilute vapors were formed, and a region where the liquid phase was present and formed dense vapors. The same analysis was performed to evaluate the process of vaporization of the spray mixture at different times from the start of injection.