Hydrogen and hydrocarbon diffusion flames in a weightless environment

An experimental investigation was performed on laminar hydrogen-, ethylene-, and propylene-air diffusion burning in a weightless environment. The flames burned on nozzles with radii ranging from 0.051 to 0.186 cm with fuel Reynolds numbers at the nozzle exit from 9 to 410. Steady-state diffusion flames existed in a weightless environment for all the fuels tested. A correlation was obtained for their axial length as a function of Schmidt number, Reynolds numbers, and stoichiometric mole fraction. The maximum flame radii were correlated with the ratio of nozzle radius to average fuel velocity. The flames of ethylene and propylene on nozzles with radii 0.113 or larger appeared to be constantly changing color and/or length throughout the test. No extinguishment was observed for any of the gases tested within the 2.2 seconds of weightlessness.