- Author
-
Hertzberg, M.
|
Litton, C. D.
|
Donaldson, W. F.
|
Kuchta, J. M.
|
Furno, A. L.
- Title
- Spectral Growth of Expanding Flames. The Infrared Radiance of Methane-Air Ignitions and Coal Dust-Air Explosions.
- Coporate
- Bureau of Mines, Pittsburgh, PA
- Report
-
RI 7779,
1973,
42 p.
- Distribution
- Available from National Technical Information Service
- Keywords
-
coal dusts
|
dust explosions
|
mine fires
|
methane
|
coal mines
|
infrared emission
- Identifiers
- radiative dynamics of explosions; experimental measurements and interpretations; radiative transport in a premixed explosion; nonadiabatic effects
- Abstract
- 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 µm. 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, ane internally consistent and are generally 50º to 200ºK below adiabatic flame temperatures. All near limit mixtures gave essentially the same flame temperatures (1,500º to 1,600ºK) 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 1,500ºK with some selective emission at 4.4 µm from hotter CO₂. The data are analyzed in terms of the radiative dynamics of a sperically 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.