An experimental and numerical study on sprays injected from two-hole nozzles for DISI engines

The objective of this study is to investigate the mixture formation process of sprays injected from two-hole nozzles for direct-injection spark-ignition (DISI) engines. Spray characteristics were examined for vapor and liquid mass distributions, spray tip penetration and spray angle using the laser absorption–scattering (LAS) technique and the computational fluid dynamics (CFD) simulation. Other characteristics including: the vapor phase concentration distribution, droplet spatial distribution and pressure distribution were acquired from the CFD simulation results. Comparison of measured and calculated results showed that as the hole-axis-angle (HAA) of the two-hole nozzle decreased, the droplet coalescence increased and vapor mass decreased. The spray with the HAA of 10° had the longest spray tip penetration and the spray with the HAA of 15° had the shortest one. The two jets of the two-hole nozzle spray had a tendency of offsetting to the central region of the spray. From 10 to 15 MPa, the increase in the injection pressure increased the vaporization rate and the spray tip penetration rate very much, but no such tendency was found when the injection pressure increased from 15 to 20 MPa.