Effects of the Initial Gel Fuel Temperature on the Ignition Mechanism and Characteristics of Oil-Filled Cryogel Droplets in High-Temperature Oxidizer Medium

The ignition mechanism was studied for a group of gel fuel compositions in a high-temperature oxidizer medium. It was determined how the initial temperature of the fuel influences the ignition characteristics. The gel fuel (oil-filled cryogel) was prepared from an oil emulsion based on the mixture of a combustible liquid and polyvinyl alcohol. The composition of primary oil emulsions was as follows: the aqueous solution of polyvinyl alcohol (5, 10 wt%) + 40–60 vol% of oil + 2 vol% of emulsifier. The initial temperature of gel fuels ranged from 188 to 293 K. Combustion was initiated in high-temperature motionless air at 873–1,273 K. Using a high-speed video recording system, we established that at different initial temperatures of the gel fuel, a set of identical processes occurs during the induction period; those are different from the same physical and chemical processes during the ignition of a combustible liquid. After reaching threshold conditions the flame spreads in the droplet’s vicinity from hot s...