AN EXPERIMENTAL STUDY OF FUEL DROPLET IGNITION

By means of photographic techniques, the size histories, ignition lags, and loci of ignition of small, single, freely falling fuel droplets suddenly exposed to a hot, oxidizing atmosphere in a furnace were determined as a function of initial droplet size, oxidizer temperature, fuel composition, and droplet spacing. The results show that ignition lag depends significantly on the temperature of the atmosphere, on the dropletdroplet spacing, and on the chemical nature of the fuel, but it appears to be only weakly affected by the oxygen concentration in the oxidizer. The ignition lag seems to be independent of the initialdroplet size if the droplets are large enough to ignite. This characteristic insures the droplets with initial diameters smaller than a characteristic value will not ignite during their lifetimes.