Ignition and Combustion Characteristics of Wall-Impinging Sprays Injected by Group-Hole Nozzles for Direct-Injection Diesel Engines

摘要

The concept of two closely spaced micro-orifices (group-hole nozzle) has been studied as a promising technology for the reduction of soot emission from direct injection (DI) diesel engines by improving the fuel atomization and evaporation. One of the main issues on group-hole nozzle is the arrangement of orifices with various distances and angles. In this study, the ignition and combustion characteristics of wall-impinging diesel sprays from group-hole nozzles were investigated with various angles between two micro-orifices (included angles). A laser absorption scattering (LAS) technique for non-axisymmetric sprays, developed based on a LAS technique for axisymmetric spray, was applied to investigate the liquid/vapor mass distribution of wall-impinging sprays. The direct flame images and OH radical images inside a high-pressure, constant-volume vessel were captured to analyze the effect of included angle on spray ignition and combustion characteristics.