- Author
- Harrington, J. E. | Shaddix, C. R. | Smyth, K. C.
- Title
- Soot in a Time-Varying Flame: Are Scattering and Extinction Measurements Sufficient?
- Coporate
- National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- Combustion Institute/Eastern States Section. Chemical and Physical Processes in Combustion. Technical Meeting, 1993. October 25-27, 1993, Princeton, NJ, 390-393 p., 1993
- Keywords
- combustion | soot | flame research | scattering coefficient | extinction | experiments | diffusion flames | flame flicker
- Abstract
- Laser-sheet scattering images of the soot region in a time-varying methane/air diffusion flame, whose fuel flow is modulated at a frequency matching the 10.13 Hz laser repetition rate, show at least a factor of ten enhancement in volume integrated scattering intensity when compared with images of a steady-state flame with the same mean fuel and air co-flows. However, only a small enhancement (~50%) appears in a comparison between the peak values of what is commonly interpreted as soot volume fraction, obtained through tomographic reconstruction of HeNe and Ar ion extinction measurements. The time-averaged soot, volume fraction in the entire flame is identical, within our measurement error, for the steady and time-varying flames. We anticipate an explanation of our scattering and extinction results based on changes in particle size and morphology induced by a different time-temperature history in the flickering flame.