AUTOIGNITION AND COMBUSTION OF A FUEL DROPLET ARRAY AT HIGH PRESSURES UNDER MICROGRAVITY

摘要

An experimental study has been performed under microgravity condition to obtain the detailed information needed for the deep understanding of the combustion phenomena of fuel droplet arrays, which autoignite in supercritical gaseous environment. The microgravity environment aboard the capsule of the drop shaft at MGLAB was utilized for the experiments. The droplet array suspended at the tip of fine quartz fibers in the cold section of the high-pressure combustion chamber was transferred quickly to be subjected to a hot gaseous medium in an electric furnace. This resulted in evaporation, autoignition and combustion of the droplet array in high-pressure and high-temperature gaseous environment. The ignition delay increased a little and the pressure effect on the ignition delay decreased with a decrease of the droplet spacing. The burning time increased monotonically with a decrease of the droplet spacing. The time period of the early stage of droplet heating was longer and the evaporation rate was lower with smaller droplet spacing. A distance between the droplet array and the outer edge of the flame formed around the droplet array was larger with smaller droplet spacing.