Ignition Characteristics of Diesel−Water Emulsion Sprays in a Constant-Volume Vessel: Effect of Injection Pressure and Water Content

The paper presents the results of experimental investigation of the effect of high injection pressure and water content on the ignition delay and lift-off length of combusting diesel−water emulsion (DWE) sprays in a constant volume chamber. DWEs with different water contents are injected at pressures up to 100 MPa into the combustion chamber under two different ambient conditions. The constant-volume chamber used allows optical access for visualization of the injection and combustion processes of the fuel. High-speed natural soot luminosity imaging is used to measure the ignition delay and lift-off length of the sprays. The experiments show that water content in the fuel and the initial temperature of the chamber have strong effects on the ignition delay and lift-off length of the emulsified sprays. Injection pressure, on the other hand, has little effect on the ignition delay but significant effect on the lift-off length.