The spectral growth of expanding flames: the infrared radiance of methane-air ignitions and coal-dust-air explosions.
Hertzberg M; Litton CD; Donaldson-WF; Kuchta JM; Furno AL
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 7779, 1973 Jan; :1-38
Results of a comprehensive study of the absolute spectral radiance of the infrared emissions from methane-air explosions are reported. The spectral growth of these expanding flames were recorded with a time resolution of 1 msec in the spectral range of 1.7 to 5.0 um. Time-resolved spectra were obtained for methane-air mixtures as a function of stoichiometry, nitrogen dilution, and halon dilution, in a 9-liter vessel under different venting conditions. Data are also presented for coal dust-air explosions. Temperatures, obtained from the absolute radiances and from a band ratio technique for methane-air, are internally consistent and are generally 50 deg to 200 deg k below adiabatic flame temperatures. All near limit mixtures gave essentially the same flame temperatures (1,500 deg to 1,600 deg k) regardless of whether the limit was obtained by dilution with excess air, excess methane, excess nitrogen, or halon. The coal dust explosion spectrum is essentially a blackbody continuum at 1,500 deg k with some selective emission at 4.4 um from hotter CO2. The data are analyzed in terms of the radiative dynamics of a spherically expanding flame zone. The importance of radiative transport is assessed. An equation is derived which relates the instantaneous fraction of combustion power radiated to adiabatic variables.
Explosions; Infrared spectra; Dust explosions; Methane; Air; Radiance; Coal dust; Flames; Flame propagation; Infrared radiation; Mine fires; Combustion; Time resolved spectroscopy
IH; Report of Investigations
NTIS Accession No.
Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 7779