A Cluster Nozzle Concept with high injection pressures for DI Diesel Engine

A combination of high pressure injection and small orifices will be one of strategies to achieve the lean combustion. But the small orifice tends to increase soot under high load conditions because of short spray tip penetration. For this reason, a cluster concept was proposed in this study. The difference of the cluster nozzle is that the cluster has several groups of orifices; each group consists of two small orifices which are very close to each other and have included-angle. The cluster nozzle was investigated with different injection pressure under part load conditions and high load conditions in a single cylinder Diesel engine and it was compared with a reference nozzle. Among the experimental results, the clusters tend to make higher smoke than the reference nozzle under conventional injection timing because the spray from the cluster with a shorter spray tip penetration loses momentum near the piston bowl. But the clusters have improved smoke emissions with higher injection pressures. With the increase of injection pressure, the clusters have a potential to reduce, to some extent, the adverse effects on spatial distribution of spray due to better fuel atomization and evaporation.