Technical Paper
Flame Lift-Off on Direct-Injection Diesel Fuel Jets: Oxygen Concentration Effects
2002-03-04
2002-01-0890
The effects of reductions in the ambient gas oxygen concentration on the flame lift-off length on direct-injection (DI) diesel fuel jets under quiescent conditions were experimentally investigated. Reductions in the ambient (i.e., in-cylinder) gas oxygen concentration occur in an engine when exhaust gas recirculation is used to reduce the emission of nitrogen oxides. Also examined were the effects of the changes in lift-off length observed for various conditions on the total amount of oxygen entrained upstream of the lift-off location, soot formation, and the relationship between fuel vaporization and combustion processes. The research was conducted in a constant-volume combustion vessel using a common-rail fuel injector and a Phillips research grade #2 diesel fuel. The lift-off length measurements show that lift-off length is inversely proportional to the ambient gas oxygen concentration.