A Theoretical and Experimental Investigation of the Ignition of Fuel Droplets

Abstract

Abstract The influence on the self-ignition of single fuel droplets of ambient temperature and oxygen concentration, droplet relative velocity, droplet size, and fuel type was investigated both experimentally and theoretically. Using a unique droplet combustion experimental system, measurements of droplet ignition delay times were obtained for two pure fuels having widely different properties (furfuryl alcohol and butyl alcohol) and two different droplet diameters (200μ and 300μ nominal diameter) for representative droplet combustion conditions. A mathematical model describing the development of profiles for fuel vapor, temperature, and oxygen in the boundary layer surrounding a single fuel droplet moving relative to a hot oxidizing atmosphere was used to correlate the observed ignition delay times. Ignition delay times are found to increase substantially with decreasing ambient temperature and to a somewhat lesser degree with increasing droplet diameter and decreasing fuel volatility. A modest tendency f...