Quantitative Analysis of Soot Formation and Oxidation Process using Laser-Induced Incandescence

A new technique using Laser-Induced Incandescence (LII) has been developed to quantify the soot concentration in a diesel engine. Characteristic problems in quantitative measurements, such as LII signal attenuation by soot clouds between the camera and the measurement plane, and incident laser attenuation due to soot clouds in the laser path, were corrected by the multi-layer correction method developed in this work. When this LII measurement method is applied to an optically accessible engine, the developing soot clouds in spray combustion can be visualized in detail. The changes in soot formation process caused by increasing fuel injection pressure with reduced hole size of injector, and by altering fuel chemical property, are both clarified quantitatively in this paper.