Effects of the Initial Heat-Up Period on a Two-Droplet Array Burning at High Pressure in Microgravity

The interactive combustion of two closely-spaced droplets at elevated pressures was investigated experimentally in a 2.2 second drop tower. Heptane, hexadecane and mixtures of the two were the fuel. A nitrogen-Oxygen ambient with a relatively low oxygen concentration faciliated observation of droplets during combustion at elevated pressures. Results show that staged combustion of binary fuel droplets still exists for interacting droplets at elevated pressures. For pure fuels, the interaction effects are principally observed during the initial heating period. For fuel mixtures, interaction effects are estimated by comparing the transition time of a single droplet to that of the droplet pair.