- Author
-
Kaplan, C. R.
|
Shaddix, C. R.
|
Smyth, K. C.
- Title
- Experimental and Computed Profiles of Soot Volume Fraction and Temperature in Laminar Methane/Air Diffusion Flame.
- Coporate
- Naval Research Laboratory, Washington, DC
National Institute of Standards and Technology, Gaithersburg, MD
- Book or Conf
- Combustion Institute. Symposium (International) on Combustion, 25th. Proceedings. Abstracts of Work-in-Progress Poster Session Presentations. Work-in-Poster Session 2. Paper 36. July 31-August 5, 1994,
Combustion Institute, Pittsburgh, PA,
Irvine, CA,
128 p.,
1994
- Keywords
-
combustion
|
soot
|
volume
|
temperature
|
laminar flames
|
diffusion flames
|
methane
- Abstract
- Comparisons are presented between experimental and computed profiles of soot volume fraction and temperature for a laminar, co-flowing, axisymmetric CH₄/air diffusion flame at atmospheric pressure. Local soot volume fractions have been measured using tomographic reconstruction of extinction data obtained at 632.8 nm as well as laser-induced incandescence images (LII), with the LII method providing superior results. Temperatures have been obtained from radiation-corrected thermocouple data. The numerical model solves the time-dependent reactive-flow Navier-Stokes equations coupled with sub-models for soot formation and radiation trnasport. Fluid convection is solved with a high-order implicit algorithm, Barely Implicit Correction to flux-corrected Transport, while thermal conduction, molecular diffusion and viscosity are evaluated with two-dimensional finite differencing. The CH₄ consumption rate is computed as a function of the local mixture fraction using Bilger's formulation, and the resulting production and consumption rates of O₂, CO₂ and H₂O are then evaluated from their respective stoichiometric coefficients. The soot volume fraction is computed as a function of the local gas properties (temperature, density, fuel mole fraction), based upon the simplified rate expressions of Syed et al. developed from measurements in steady CH₄/air flames. These expressions consider the effects of nucleation, surface growth, coagulation, and oxidation. The radiative heat flux is found by solving the radiation transfer equation using the Discrete Ordinated Method and includes radiative effects from soot, CO₂, and H₂O.