LAMINAR SMOKE POINTS OF COFLOWING DIFFUSION FLAMES IN MICROGRAVITY

Abstract

Nonbuoyant laminar jet diffusion flames in coflowing air were observed aboard the International Space Station with an emphasis on laminar smoke points. The tests extended the 2009 Smoke Points In Coflow Experiment (SPICE) experiment to new fuels and burner diameters. Smoke points were found for methane, ethane, ethylene, and propane burning in air. Conditions included burner diameters of 0.76, 1.6, 2.1, and 3.2 mm and coflow velocities of 3.0 - 47 cm/s. This study yielded 57 new smoke points to increase the total number of smoke points observed to 112. Smoke point lengths were found to scale with burner diameter raised to the -0.67 power times coflow velocity raised to the 0.27 power. Sooting propensity was observed to rank according to methane < ethane < ethylene < propane < 50% propylene < 75% propylene < propylene. This agrees with past normal gravity measurements except for the exchanged positions of ethylene and propane. This is the first time a laminar smoke point has been observed for methane at atmospheric pressure.