- Author
-
Jeng, S. M.
|
Chen, L. D.
|
Faeth, G. M.
- Title
- Investigation of Axisymmetric Buoyant Turbulent Diffusion Flames: Turbulence Properties and Concentrations of Major Species. October 1982.
- Coporate
- Pennsylvania State Univ., University Park, PA
- Sponsor
- National Bureau of Standards, Gaithersburg, MD
- Report
-
NBS GCR 83-422,
February 1983,
73 p.
- Distribution
- Available from National Technical Information Service
- Contract
- GRANT-NB81NADA2044
- Keywords
-
ceilings
|
diffusion flames
|
fire models
|
flame impingement
|
methane
|
propane
|
turbulence
|
chemical equilibrium
- Abstract
- Earlier measurements of mean velocities and temperatures in buoyant, turbulent, axisymmetric methane diffusion flames burning in still air were extended to include measurements of fluctuating velocities and mean species concentrations (CH4, N2, CO2, H2O, CO and H2). These measurements, as well as existing measurements in turbulent propane diffusion flames, were employed to evaluate differential models of the process including: (1) a base k-epsilon-g model where effects of buoyancy are only considered in the governing equations for mean quantities; and (2) an extended k-epsilon-g model where buoyancy is also considered in the governing equations for turbulence quantities. Two methods for determining state relationships (the variation of scalar properties as a function of mixture fraction) used in these models were also evaluated: (1) the laminar flamelet approach, where scalar properties are found from measurements in laminar diffustion flames; and (2) the partial equilibrium approach, where scalar properties are found from chemical equilibrium calculations for fuel equivalence ratios less than a critical value, phi c, and from frozen adiabatic mixing calculations for fuel equivalence ratios greater than this value. After choosing phi c = 1.2, all the models provided reasonably good predictions of mean velocities, temperatures and species concentrations in both methane and propane diffusion flames.