Modeling microexplosion mechanism in droplet combustion: Puffing and droplet breakup

This study improved existing models by conducting experiments to determine breakup delay, child droplet dynamics, and the effect of microexplosion. Direct imaging was used, and droplets were suspended on a holder. The initial droplet diameter was between 0.5 and 1 mm, the temperature ranged from 700 to 1500 K, and the concentration of water in combustible liquid varied from 5 to 15 wt%. The process of microexplosion was simplified to interpret experimental results by assuming that water subdroplets were spherical and located in the center of a spherical nonemulsified fuel droplet and that water subdroplets can be present anywhere in the emulsified fuel droplet. The modeling results are consistent with the experimental results. The predicted and experimental droplet breakup times differed by 15 wt% or less for nonemulsified fuels and by 35 wt% or less for emulsified fuels. The postbreakup analysis revealed the microexplosion strength and its effect on child droplets. The prediction of microexplosion strength K was based on the superheating of water subdroplets. This model accounts for almost all parameters to approximate experimental results. This study improved the models of microexplosion to facilitate their use in the secondary atomization of multicomponent fuels.