Abstract:

Numerical and experimental studies were carried out on a 2L HPCR diesel engine to explore the effects of fuel injection pressure on the processes of fuel spray, air-fuel mixing and the formation of harmful emission. Results show that, as the injection pressure increases, the spray penetration increases, the Sauter Mean Diameter (SMD) of fuel drips significantly decreases, and the atomization quality is improved. Furthermore, with the increase in injection pressure, the diffusion capability of fuel is improved, the distribution volume increases and the oxidation of soot is enhanced. On the whole, with the increase in fuel injection pressures, the soot emission is reduced and the NO emission is deteriorated. However, the increase in injection pressure can result in higher degree of fuel richness in early period of combustion and further deterioration of air-fuel mixing. When the injection pressure reaches a certain level, it can weak the sensibility of its influence on soot emission.

Key words: power engineering, diesel engine, injection pressure, spray, air-fuel mixting, computational fluid dynamics (CFD)