Theoretical analysis and predictions of burning in microgravity using a burning emulator

摘要

Burning experiments are analyzed for 29 steady burning flames using a gas burner (BRE) to emulatecondensed-phase burning of 25 mm diameter flat surface. Mixtures of ethylene and nitrogen allow for23.6 and 47.2 kJ/g heats of combustion ( LHV ). Ambient conditions range from 21 to 40% oxygen andpressures of 0.56 to 1 bar. The results are compared to predictions from analytic models developed todetermine the flame radiation fraction, flame convective and radiative heat fluxes, flame shape, and heatsof gasification for steady burning. Steady burning is theoretically decided by ensuring the flame temperatureis above a critical value of 1100 K. Good agreement is achieved between experiment and predictedsteady results. Further computations are made to determine the effect of ambient pressure and oxygenon burning for heats of combustion of 23.6 and 47.2 kJ/g, diameters up to 100 mm, and vaporizationtemperatures of 80 and 350 ℃. It is found that for the range of analyzed conditions, heats of gasificationof about 1 to 5 kJ/g, steady burning would result over a range of about 1 to 6 g/m~2 s. Low pressureappears to yield more stable flames. The results have implications on how the fire safety of materials inmicrogravity should be determined.