- Author
-
Jeng, S. M.
|
Lai, M. C.
|
Faeth, G. M.
- Title
- Investigation of Axisymmetric Buoyant Turbulent Diffusion Flames: Flow Structure and Radiation Properties.
- Coporate
- Pennsylvania State University, University Park, PA
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
-
NBS GCR 84-458,
January 1984,
95 p.
- Distribution
- Available from National Technical Information Service
- Contract
- NB81NADA2044
- Keywords
-
buoyancy
|
diffusion flames
|
flame research
|
radiative heat transfer
- Abstract
- A theoretical and experimental study of flow structure and nonluminous radiation properties of turbulent, buoyant, axisymmetric, methane diffusion flames burning in still air is reported. Past measurements of velocities, temperatures and species concentrations in the same buoyant flames were used to evaluate a Favre-averaged k- -g turbulence model of the process - with all empirical constants fixed by earlier measurements in noncombusting flows. The model yielded reasonably good predictions of mean properties. Turbulence predicitons were less satisfactory, generally underestimating fluctuation levels and Reynold stress in highly buoyant regions of the flow. Spectral radiance was measured along radial paths within and near the luminous portion of the flames. Predictions of spectral radiance were found by solving the equation of radiative transfer along the same paths. A narrow-band model was used with flow structure predicted by the conserved scalar formalism of a k- -g turbulence model. The computations were based on mean propeties as well as stochastic method which allowed for turbulent fluctuations. In general, the stochastic method overestimated the measured spectral radiances by 10-20%, while the mean property method overestimated them quite well. Therefore, while turbulent fluctuations have a significant influence on nonluminous radiation properties of the present flames, the effect is comparable to uncertainties in current flame structure and narrow-band models.