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 press ures was investigated experimentally in a 2.2 second drop tower. Heptane, h exadecane and mixtures of the two were the fuel. A nitrogen-oxygen ambient with a relatively low oxygen concentration facilitated observation of dropl ets during combustion at elevated pressures. Results show that staged combu stion of binary fuel droplets still exists for interacting droplets at elev ated pressures. For pure fuels, the interaction effects are principally obs erved during the initial heating period. For fuel mixtures, interaction eff ects are estimated by comparing the transition time of a single droplet to that of the droplet pair.