Characteristic of diesel spray combustion and soot formation using laser-induced incandescence

Abstract

The planar distribution images of diesel spray combustion flame and soot formation were measured and analyzed by using laser-induced incandescence (LII), in a high-temperature high-pressure constant volume combustion bomb. The effects of combustion flame and fuel gas mixing characteristics on soot formation and distribution was studied, under different ambient condition of constant volume combustion bomb and injection pressure. Result indicates that, with increasing ambient temperature and pressure, the ignition delay of diesel fuel becomes shorter. Air entrainment in the diffusion combustion flame lift-off is one of the most important factors affecting soot formation and evolution. Increasing ambient temperature and pressure and decreasing injection pressure shorten the diesel flame lift-off. High injection pressure and low ambient temperature and pressure generate low LII signal intensity, indicating small soot volume fraction. Naturally forming mixture concentration and temperature stratification in spray mixing process influence not only on ignition and combustion processes, but also soot formation. The study provides valuable basis for optimization design of combustion system and verification of combustion models. Show more