Micro-explosive combustion and flame spread of Jatropha oil/2, 5-dimethylfuran (DMF) blended fuel droplet array

Abstract

The micro-explosive combustion and flame spread characteristics of a multi-component fuel droplet array are investigated using high-speed backlight imaging technique. The multi-component blends consist of 2, 5-dimethylfuran (DMF) as a lower volatile component, while Jatropha oil is used as the higher volatile constituents. Three droplets (droplet array) with the same diameter are horizontally arranged at equal intervals using fiber support method. The effects of normalized droplet spacing (S/d0) and DMF concentration on multiple droplets micro-explosive combustion and flame spread are also analyzed. The results show that the interaction between multiple droplets combustion can not be ignored under small S/d0. It increases with the increase of DMF concentration and the decrease of S/d0. When the S/d0 is constant, the interaction between droplets depends on the duration of simultaneous combustion of multiple droplets and the number of droplets surrounded by the same flame. Due to the micro-explosion, the average flame spread velocity of Jatropha oil-DMF blended fuel droplet array decreases monotonously with S/d0 in normal gravity, which is different from that in microgravity. Four flame spread modes of droplet array containing micro-explosion are found: full-envelop flame, sequential full-envelop flame, semi-envelop flame to independent flame and independent sequential flame.