Diesel spray auto-ignition in different oxidizing atmospheres

Abstract

• Diesel spray auto-ignition in different oxidizing atmospheres were studied. • Diesel exhibits the strongest auto-ignition tendencies in the O 2 /Ar atmosphere. • Ambient temperature/pressure has consistent effects on ignition in all atmospheres. • Effects of injection pressure on ignition are dependent on oxidizing atmosphere. Understanding diesel ignition characteristics in advanced combustion modes is of great significance to achieve efficient diesel combustion. In this study, diesel spray auto-ignition characteristics were studied in three oxidizing atmospheres comprised of O 2 /N 2 , O 2 /Ar, and O 2 /CO 2 mixtures, respectively. The experimental results reveal that the diesel auto-ignition tendency and combustion intensity in the three oxidizing atmospheres are listed in the order of the O 2 /Ar atmosphere > the O 2 /N 2 atmosphere > the O 2 /CO 2 atmosphere. In all the oxidizing atmospheres, fuel ignition delay and combustion delay are shortened with increased ambient temperature and pressure. However, the effects of injection pressure on fuel auto-ignition processes are dependent on the oxidizing atmosphere. In the O 2 /CO 2 atmosphere, the combustion delay firstly increases and then decreases with increased injection pressure, for the coupling effect of fuel burn duration and burn rate, while in the O 2 /N 2 and the O 2 /Ar atmospheres, the combustion process is insensitive to changed injection pressure.