- Author
- Morehart, J. H. | Zukoski, E. E. | Kubota, T.
- Title
- Characteristics of Large Diffusion Flames Burning in a Vitiated Atmosphere.
- Coporate
- California Institute of Technology, Pasadena
- Book or Conf
- International Association for Fire Safety Science. Fire Safety Science. Proceedings. 3rd International Symposium. July 8-12, 1991, Elsevier Applied Science, New York, Edinburgh, Scotland, Cox, G.; Langford, B., Editors, 575-583 p., 1991
- Keywords
- fire research | fire safety | fire science | laminar flames | diffusion flames | room fires | combustion products | flame length | extinction | fire models | natural gas | ethylene | oxygen concentration
- Abstract
- Experiments concerning properties of large diffusion flames burning steadily in a vitiated atmosphere under conditions similar to those which may arise in a room fire are described. The effects of vitiation on the products of combustion and flame lengths, and the extinction limits are described for natural gas and ethylene diffusion flames stabilied on 8.9-, 19- and 50-cm pool-type burners. As vitiation was increased and the flame extinction limit was approached, the flame length increased slightly. Close to the limit, radiation from soot in the flame became imperceptible, leaving only a weakly luminous blue flame. Even with significant reductions in both the flame height and luminosity near the limit conditions, the hydrocarbon fuels were completely oxidized in the flame to water and carbon dioxide and no measurable concentrations of products of incomplete combustion were produced. A comparison of limiting oxygen concentrations and limiting flame temperatures for these experiments with the results of other investigations shows reasonably good agreement despite widely varying experimental techniques. These results are contrasted with those obtained in the unsteady situation which arises when a large buoyant diffusion flame burns in an enclosed space such that the upper part of the flame is in a strongly vitiated layer composed of a mixture of air and products of combustion, and the lower part in fresh air.