Flame-Spread Characteristics of n-Decane Droplet Arrays at Different Ambient Pressures in Microgravity

Abstract

This research involves microgravity experiments being conducted on flame spread over fuel droplet arrays at different pressures including low-pressure condition in order to improve understanding of flame-spread characteristics under high-altitude relight condition of jet engines. n-Decane was used as a fuel. The ambient pressure ranged from 25 to 200 kPa. The results show that the flame-spread rate and flame-spread-limit distance decreased with an increase in ambient pressure. As the ambient pressure is increased, the thermal conduction time from the flame of a droplet to the next unburned droplet increases due to the decreased thermal diffusivity, and the droplet heating time also increases due to the increased fuel boiling point, resulting in a decrease in the flame-spread rate and -limit distance. The pressure effect on the flame-spread limit around two interactive burning droplets is also discussed.