Measurement of droplet size distribution of gasolinedirect injection spray by droplet generator and planar imagetechnique

Abstract

To understand the spray characteristics that are related tothe characteristics of emissions and the combustion of directinjection engines, the planar image technique was applied to measurethe distribution of droplet size. This technique was based on theprinciples of laser-induced fluorescence (LIF) and the Mie scatteringof droplets in the spray. We decided to apply the LIF and Miescattering intensity indices for unleaded gasoline to this techniquewith a droplet generator. The fluorescence and scattering signalswere imaged simultaneously by an optical system composed of adoubling prism, optical filters and an ICCD camera. Relative Sautermean diameter distributions according to space and time were obtainedby calculating the ratio between two light intensities, and thedistributions were quantified with a laser diffraction particleanalyser. Experimental results have shown that the characteristics ofthe gasoline direct injection injector varied with injectionpressure.