Flame extinction and low-temperature combustion of isolated fuel droplets of n-alkanes

A numerical model describing the combustion of isolated fuel droplets in microgravity based on a detailed kinetic mechanism is presented. The role of the initial diameter of the droplet and the amount of oxygen on the gaseous atmosphere on radiative extinction and formation of stable cool flames around the droplet were studied. The squared critical diameter linearly increased with the mole fraction of oxygen in the atmosphere. While no significant differences in the critical diameters were observed for n-heptane and n-decane ithe inert species in the gaseous atmosphere played a major role promoting or inhibiting the tendency to radiative extinction. Predictions and experimental measurements showed good agreement showing that only droplets with an initial diameter larger than a critical diameter undergo radiative extinction.