On the burning and microexplosion of collision-generated two-component droplets: miscible fuels

The combustion and microexplosion of freely falling two-component droplets, generated either independently or through the collision or merging of two droplets of the two fuels have been studied experimentally. The results show that the non-disruptive combustion characteristics, including the ignition delay, the flame shrinkage and the burning rates are largely similar for droplets generated with these two different modes, hence indicating the efficiency of mixing through the internal motion produced when droplets coalesce. Microexplosion induced by internal superheating and hence nucleation, however, was only observed for the collision-generated droplets, and is believed to be initiated by the air bubbles entrained during a collision. The potential importance of bubble entrainment during droplet and spray generation on spray atomization and burnout is emphasized.