Spontaneous Ignition Delay of a Fuel Droplet in High Pressure and High Temperature Gaseous Environments

Experimental and theoretical studies on the ignition delay of a single droplet in high pressure gaseous environments were carried out. In the experiments, a movable furnace was dropped over a droplet to cause the ignition and the measurement of ignition delay was made for normal paraffin hydrocarbon droplets at 0 atg40 atg of ambient gas pressure and 220°C700°C of ambient gas temperature. Experimental data were correlated with the following expression. [numerical formula] where P, T, and φd are pressure, and temperature and oxygen concentration of ambient gas of which increase makes the ignition delay short. Ignition delay was independent of droplet size and increased with an increase in the number of carbon atom in a molecule of fuel. In the theory, a model was developed for droplet ignition, which consisted of the evaporation of a droplet and ignition of homogeneous gas mixture, and ignition delay was calculated. Both the experimental and the theoretical results showed reasonable agreements.