Microexplosion of a suspended Al/liquid fuel slurry droplet was experimentally studied in a combustor with electric heater of which temperature was controllable. The mechanism of microexplosion and the effects of surfactant on evaporation and shell formation, have been examined for two liquid fuels with various surfactant concentrations and solid loadings. Liquid fuels have different boiling points the surfactant has the pyrolysis temperature. Surfactant pyrolysis is found to play a significant role in shell formation as well as microexplosion. Transient internal temperature distributions for slurry droplets were measured. As the internal temperature of the droplet with surfactant continuously rises, the outer region temperatures reaches over the boiling point of n-Heptane, and then microexplosion occurs since the outer region is superheated.
As the liquid fuel evaporates, the small solid particles are inter linked to form a tightly packed shell due to surfactant pyrolysis. Since the shell textures are weak and permeable, the envelope flame is formed around the droplet. The effects of two aligned droplets on the interactive vaporization, combustion and microexplosion are also sought here. And the effect of the outer radiative heat source addition to convective heat transfer on microexplosion of droplets is investigated in low Reynolds number flow by using the electric heater. When the heater surface temperature was above 1000K, the microexplosion time starts to be reduced due to outer radiation. The ignition, combustion and microexplosion characteristics of a single droplet as well as the interactive microexplosion of binary droplets is studied. The microexplosion time of binary slurry droplets is found to be less than that for the isolated droplet due to radiation interaction between the droplets.
