Combustion of decane-based slurries with metallic fuel additives

Low density slurries based on decane were prepared using micron-sized powders of mechanically alloyed Al_0.7Li_0.3, nanocomposite 2B+Ti, and pure aluminum as additives. The slurries were atomized using an ultrasonic nozzle. The produced aerosol was focused into a laminar, vertically rising jet and ignited in air to produce a lifted laminar flame. The flames of different slurries and pure decane were studied optically. It was found that in this configuration aluminum is difficult to ignite. The powders of mechanically alloyed Al_0.7Li_0.3 and nanocomposite 2B+Ti ignited readily and burned within the hydrocarbon flame resulting in an increased flame temperature and length. Based on the visualized streaks, burning metal particles were well separated within the flame. The ignition of nanocomposite 2B+Ti particles was accompanied by rapid heat release and often followed by the micro-explosions of ignited particles. The ignition delays of nanocomposite 2B+Ti particles were determined by the time of evaporation of liquid fuel droplets in which metallic additives were contained. Ignition and combustion of the mechanically alloyed Al_0.7Li_0.3 was assisted by selective oxidation of Li. The flame length was controlled by the fuel and oxidizer diffusion rates. The flames containing actively burning metallic additives, i.e., mechanically alloyed Al_0.7Li_0.3 and nanocomposite 2B+Ti powders, were longer than the pure decane flames and decane/Al slurry flames. The increased flame length indicated an additional consumption of oxidizer in the jet's center, where metallic particles were concentrated.