高速直喷柴油燃烧系统潜在的碳烟和一氧化碳减排方法
The current direction for Diesel combustion systemdevelopment is towards homogenization, in order toreduce particulate and NOx emissions. However, astrong increase of carbon monoxide emissions (CO) isfrequently noted in combination with enhancedhomogenization.Therefore, the current investigation focuses on adetailed analysis of the particulate - CO trade-off using alaser-optical and multidimensional CFD investigation ofthe combustion process of a swirl HSDI system. TheCFD methodology involves reduced kinetics for sootformation and oxidation and a three-step CO model.These models are validated by a detailed comparison tooptical measurements of flow, spray penetration and thespatial distribution of soot, temperature and oxygenconcentration.The results obtained show that high concentrations ofCO occur as an intermediate combustion reactionproduct. Subsequently, CO and soot are oxidized inlarge areas of the combustion chamber. In part loadoperation, CO emissions are mainly caused by dilutioneffects in the early phases of combustion. However, theengine’s soot emissions are caused by insufficientoxidization.Soot generation and oxidation are found to be stronglyimpacted by the slight non-homogeneity of the swirlmotion. The gaseous emissions are not affected by thesmall differences in local flow, which are outlined furtherin the text.