C. M. Sliepcevich

Bending of wind-blown flames from liquid pools

The bending of a flame by wind influences the amount of heat transferred by radiation and convection, the fuel burning rate, and the flame spread rate. To what extent will a flame be bent by wind? The author presents correlations of data taken from liquid pool fires, which enable us to predict flame bending and trailing for large fires.

The piloted ignition of wood by thermal radiation

Previous experimental studies on the ignition of dry wood by thermal radiation show poor agreement because all of the primary variables have not been monitored, and consequently they are not included in the resulting correlations. Although the density of the wood, the thickness of the specimen, and the magnitude of the incident irradiance have generally been recognized as principal parameters, there is little evidence in the literature that the spectral absorptance of the wood relative to the spectral quality of the incident radiation has been appreciated as a dominant variable. Therefore, the purpose of this investigation was to examine the significance of all of these variables. Piloted ignition data were obtained for thirteen dry wood species having thicknesses from less than 0.2 cm to more than 2.5 cm and densities from less than 0.1 g/cm 3 to more than 1.0 g/cm 3 . Diffusion flames and high-temperature tungsten lamps were used as sources of thermal radiation at incident irradiances from about 0.6 cal/cm 2 -sec to about 3.5 cal/cm 2 -sec. The spectral absorptances of the wood samples were measured in order to calculate an average absorptance over the range of spectral quality of the incident radiation. The ignition data were correlated on the basis of relationships suggested by considering the wood specimens as infinite slabs of inert, opaque material. It was found that, when the density, thickness, and absorbed irradiance were included in the correlation of the experimental data, a unique ignition correlation could be defined.

Synergism between chemical and physical fire-suppressant agents

A pronounced synergism is reported for mixtures of physical and chemical agents used in flame extinguishment. Mixtures containing approximately 90% (by volume) of either carbon dioxide or nitrogen and 10% of CF3Br or CF2ClBr are much more effective in suppressing fires (in cup-burner tests) than would be predicted by an additivity of effects. A method is proposed for delivering solutions of chemical agents dissolved in liquid CO2 to obtain cooperative fire-suppression effects, while simultaneously reducing the danger to humans and the environment. A simple model has been developed to give very good predictions of the extinguishment concentrations of mixtures of physical and chemical agents.

The irradiation and ignition of wood by flame

The generally accepted models on the ignition of wood are not valid. So say the authors, who present an improved model, which correlates data on five different woods.

The effect of wind on flames

A simplified and improved correlation for the drag coefficient of windblown natural gas flames is given. Experimental results leading to the correlation were obtained in a low-speed wind tunnel specifically designed for such studies at the University of Oklahoma North Campus.

Burning rates and heat transfer from wind-blown flames

In the first of this two-part series, the authors discussed the effects of wind on flame bending and trailing. This paper describes investigations of liquid fuel burning rates, flame lengths, wake gas temperatures, and flame radiation. Data are taken from the liquid pool fires described in the earlier article.

Interaction effects of multiple pool fires

What are the effects of flame behavior of a number of fires burning in close proximity to one another? The results of measurements of burning rates, heat feedback, flame height, and flame trailing are reported for fires involving liquid pools.

Ignition of alpha-cellulose and cotton fabric by flame radiation

Spectral emission characteristics of radiation affect the ignition behavior of flammable materials subjected to the same incident irradiance levels from different irradiating sources. Experimental flame radiation results were obtained in an ignition cabinet utilizing sheets of flames as the irradiating source.

An experimental technique for the ignition of solids by flame irradiation

In spite of advice to the contrary, the authors spent two years developing a flame ignition cabinet, which throws a new light on ignition criteria. That the cabinet gives good results has been established by comparison with data obtained by others on nonflame ignitions.

Interaction effects of wind-blown flames from wood crib fires

In the past, the authors and their colleagues have studied the effects of wind-blown flames involving burning gases and liquid pool fires. It would seem logical to conduct a similar study with solid fuels. This the authors have done, and they report their observations here.