Flame spread upward

Physically <5f is the flame extension over the new material to ignite. This is illustrated for a match flame, spreading upward or downward in Figure 8.5 or as suggested in Figure 8.1. We shall see that the visible flame is a measure for <5f because at the flame tip in a turbulent flame the temperature can drop from 800 °C in the continuous luminous zone to... 

Flames were first observed at or near an unoccupied caboose. A flash fire resulted, propagating toward the punctured car area. An orange flame then spread upward, and a large vapor cloud flared with explosive force. Estimates of the time lapse between these occurrences range from 2 to 30 seconds. Almost immediately thereafter, a second, more severe, explosion was reported. ... 

For the greatest effect on wooden structures, the mixture should be in a pile, never spread out in a thin layer. It should be placed beneath the target material, if possible, so the flames will spread upward. In a packing box or room, a comer is a good place to start the fire. 

Saito. K., Quintiere, J.G., Williams, F.A., "Upward Turbulent Flame Spread", Int. Assoc, for Fire Safety Science. Fire Safety Science Proceedings. 1st Int. Symposium. October 7-11 1985. Grant, C. E., and Pagni, P. J.,... 

Kulkarni, A. K., Fisher, S., "A Model for Upward Flame Spread on Vertical Wall", National Bureau of Standards, Center for Fire Research, Gaithersburg, 1988. 

The Ahmad and Faeth [18] data encompass alcohols saturated into an inert wall of xp up to 150 mm and xf up to 450 mm. Typically, qf is roughly constant over the visible flame extension (4) with values of between 20 and 30 kW/m2. The same behavior is seen for the radiatively enhanced burning of solid materials - again showing q values of 20-30 kW/m2 over 4 for Xf up to 1.5 m. These data are shown in Figure 8.13. Such empirical results for the flame heat flux are useful for obtaining practical estimates for upward flame spread on a wall. 

Quintiere, J.G., Harkleroad, M. and Hasemi, Y., Wall flames and implications for upward flame spread, Combust. Sci. Technol., 1986, 48, 191-222. 

By far the most common and most practical approach to measure the rate of flame spread over a flat surface involves recording the location of the flame tip (wind-aided spread) or flame front (opposed-flow spread) as a function of time based on visual observations. However, in the case of wind-aided flame spread, it is very difficult to track propagation of the pyrolysis front (boundary between the pyrolyzing and nonpyrolyzing fuel) as it is hidden by the flame. This problem can be solved by attaching fine thermocouples to the surface at specified locations as ignition results in an abrupt rise of the surface temperature. This approach is very tedious and not suitable for routine use. An infrared video camera has been used to look through the flame and monitor the upward advancement of the pyrolysis front in a corner fire.62... 

Hasemi, Y., Experimental wall flame heat transfer correlations for the analysis of upward wall flame spread. Fire Science and Technology 1984,4, 75-90. 

Qian, C., Ishida, H., and Saito, K., Upward Flame Spread Along the Vertical Comer Walls. NIST-GCR-94-648, National Institute of Standards and Technology Gaithersburg, MD, 1994. 

One of the simplest large-scale geometries relevant to real world fire growth modeling is vertical upward flame spread on a free-standing wall, meaning that the wall is not part of a compartment. Compartment effects, such as accumulation of a hot ceiling layer, do not come into play. 

Zhang, J., Dembele, S., Karwatzki, J., and Wen, J.X. Effect of radiation models on CFD simulations of upward flame spread. In Gottuk, D.T. and Lattimer, B.Y. (eds.) Proceedings of Eighth International Symposium on Fire Safety Science, September 18-23. Beijing, China International Association for Fire Safety Science, 2005, pp. 421 132. 

Consalvi, J.L., Pizzo, and Porterie, B. Numerical analysis of the heating process in upward flame spread over thick PMMA slabs. Fire Safety Journal, 2008. 43, 351-362. 

In contrast to downward spread, upward spread of flames along vertical fuel surfaces usually is acceleratory. Rates of heat transfer to the fuel by radiation and conduction from the luminous flames of height /, that bathe the surface are so great that, in comparison, transfer elsewhere can be neglected in the first approximation. If q is the average normal energy flux from these flames to the surface, then from geometric considerations, q — (l/L)q for the q in equation (67), where L is the thickness of the fuel... 

The flame spread rate depends on the orientation of the specimen which can be horizontal, vertical or at some angle to the horizontal direction. A vertically mounted specimen can burn upward or downward, so that two categories of results can be obtained. When the edges of the specimen are exposed, the combustion is more rapid than that of a specimen with inhibited edges (i.e. the edges are covered by a noncombustible material). 

Ohlemiller, T. Cleary, 1999. Upward flame spread on composite materials. Fire Safety Journal 32(2) 159-172. 

Fernandez-Pello, A.C., 1977. Upward Laminar Flame Spread Under the Influence of Externally Applied Thermal Radiation.Science and Technology 17(3-4) pp. 87-98. 

K. Saito, X. G. Quintiere, F. A. Williams. 1985. Upward turbulent flame spread, in Proceedings of the First International Symposium on Fire Safety Science, pp. 75-86. 

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