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Radiance, soot, and temperature interactions in turbulent alcohol fires

1989; Elsevier BV; Volume: 22; Issue: 1 Linguagem: Inglês

10.1016/s0082-0784(89)80135-3

1878-027X

Stephen J. Fischer, William L. Grosshandler,

Combustion and Detonation Processes

The fires above 0.5 meter pools of isopropanol and ethanol have been studied experimentally to determine the time-averaged composition of radiating gases and soot, the fluctuating temperature distribution functions, and the radiation which leaves the flames. Temperature is determined from a thermocouple rake, permitting correlation of the temperatures at eleven positions along the fire diameter. Digitized time-lapse photographs enhance the understanding of the visible radiation in the fire. In both fires, the peak average temperature is about 1275 K with a standard deviation close to 300 K, and the dominant flickering frequency is near 2 Hz. Significant differences in the fires exist: the thermal output of the isopropanol is 131 kW, double the ethanol fire; the peak radiance from the isopropanol is 17 kW/m2/sr, also double the ethanol value; the maximum local monochromatic soot extinction coefficient in the isopropanol fire is 7.8 m−1, ten times that of ethanol; and the gray absorption coefficients are calculated to differ by a factor of four in the two fires. Two alternative models are proposed for the soot absorption coefficient: steady-state soot kinetics on the fuel rich side of the flame front coupled with frozen chemistry where the fuel concentration is low, and a model which ties the soot level directly to the carbon monoxide concentration.