High pressure droplet burning experiments in reduced gravity

Abstract

The paper summarizes research on high pressure burning of single fuel droplets and describes recent results obtained under normal and reduced gravity conditions with suspended droplets. Parabolic flights were used to create a reduced gravity environment. Droplet burning experiments using methanol, n-heptane, n-hexane and n-octane were performed at ambient air temperature and pressures in the range of 0.1 MPa to 12 MPa. The combination of high pressure droplet burning experiments with reduced gravity is crucial in order to reduce the pressure enhanced natural convection effects and also to extend the applicability of the fibre suspended droplet technique when the surface tension decreases due to the closeness of thermodynamic critical conditions. The experimental results presented in this paper show a decrease of the droplet burning time with pressure in the subcritical domain. The minimum burning time observed by other investigators around the critical pressure was not found in this study for the four fuels investigated. This may be attributed to the pressure enhanced natural convection effects due to the residual gravity during parabolic flight experiments.