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Talk Abstract
Contribution to the Understanding of Wall Burning: Past and Present Work in Poitiers

Pierre Joulain
Laboratoire de Combustion et de Détonique (LCD) ­ UPR 9028 CNRS
ENSMA - Université de Poitiers ­ Téléport 2
BP 40109 ­ 1 Avenue Clément Ader
86961 Futuroscope Cedex ­ France
joulain@lcd.ensma.fr


In this presentation I intend to summarize the main features of my contribution to the understanding of wall burning. After giving a brief overlook of my earlier research in the field, I will mainly focused my talk on the burning of vertical walls and also on some aspects of the interaction between a pool and a vertical burning wall fire, the interaction of two burning walls. The numerical study of the turbulent burning of one or two walls with fire induced buoyant flow will be of major concern. More precisely I will present in more detailed the numerical study recently conducted to investigate the fire structure, heat transfer and pyrolysis rate in such a situation. The strong coupling of the two initially unknown parameters, such as the burning and the fire induced mass flow rates, is modeled using a parabolized numerical technique which takes into account the effects of the streamwise pressure gradient. Transport equation for mass, momentum, gas- phase chemical species, enthalpy are solved using a finite volume method. The turbulent flow field is solved using a standard k- epsilon turbulence model in conjunction with a wall function. A two dimensional adaptation of the discrete ordinates method is used for estimating the flame radiation energy to the burning wall. Soot model is also included in order to permit application to radiative heat transfer within the flame. The results indicate that with decrease of the wall spacing/height ratio (L/H), convection flux decreases slightly, whereas, contribution by radiation increases considerably from 70 to 90% of the total heat feedback to the pyrolyzing surface. Of particular interest is a maximum local burning rate for a L/H = 0.1, due to enhanced convection and radiation fluxes. I will conclude the presentation by some observations and results corresponding to work in progress about the influence of cross-flow, gravity, and of width, confinement and pyrolysis length on the characteristics of this kind of wall fires.

REFERENCES

1) KIM JIN KON, MOST J.M., JOULAIN P., Heat and mass transfer in a fully developed boundary layer along a burning vertical wall. Proceedings 8th International Heat Transfer Conference, San Francisco, Vol. 3, p. 1133-1138, 1986.

2) MOST J.M., BELLIN, B., JOULAIN P., SZTAL B., Interaction between two burning vertical walls. Proceedings Second International Symposium on Fire Safety Science, Publication IAFSS, p. 285-294, 1988.

3) ANNARUMMA M., MOST J.M., JOULAIN P., Velocity and temperature measurements in a bidimensionnal pool fire: Influence of a vertical wall close to the fire², Progress in Astronautics and Aeronautics, Vol.132, p. 314-338, 1991.

4) ANNARUMMA M., MOST J.M., JOULAIN P., On the numerical modeling of buoyancy dominated turbulent vertical diffusion flames, Combustion and Flame, Vol.85, p. 403-415, 1991.

5) WANG H.Y., JOULAIN P., MOST J.M., Three dimensional modeling and parametric study of turbulent burning along the walls of a vertical rectangular channel Combustion Science and Technology, Vol. 109, p. 287-308, 1995.

6) JOULAIN P., Review article, Convective and radiative transport in pool and wall fires: 20 years of research in Poitiers Fire Safety Journal, Vol. 26, p. 99-149, 1996.

7) WANG H.Y., JOULAIN P., Three dimensional modeling for prediction of wall fires with buoyancy induced flow along a vertical rectangular channel, Combustion and Flame, Vol.105, p. 391-406, 1996.

8) WANG H.Y., JOULAIN P., ³Modeling on the interaction of the turbulent diffusion flames between a vertical burning wall and a pool fire Proceedings of the Fifth International Symposium on Fire Safety Science, Publication IAFSS, p.475-486, 1997.

9) KOLB G., TORERO J.L., MOST J.M., JOULAIN P., Cross flow effects on the flame height of an intermediate scale diffusion flame, Proceedings International Symposium on Fire Science and Technology (ISFST¹97), Seoul, Korea, November 1997, p. 169-176.

10) JOULAIN P., The behavior of pool fires: State of the art and new insights, Topic Review Paper, Twenty-Seventh Symposium (International) on Combustion, The Combustion Institute, Pittsburgh, PA, p. 2691-2706, 1998.

11) WANG H.Y., JOULAIN P., MOST J.M., Modeling on burning of large-scale vertical parallel surfaces with fire induced flow, Fire Safety Journal, Vol. 32, p. 241-271, 1999.

12) VIETORIS T., JOULAIN P., TORERO J.L., Experimental characterization of a laminar diffusion flame in microgravity, Journal de Chimie Physique, Vol.96, p. 1022-1030, 1999.

13) VIETORIS T., JOULAIN P., TORERO J.L., Experimental observations on the stability of a laminar diffusion flame in microgravity, Paper A13 presented at the Sixth International Symposium on Fire Safety Science, Poitiers July 5-9, 1999, accepted for publication in the Proceedings, Publication IAFSS.

14) WANG H.Y., TORERO J.L., JOULAIN P., Calculation of vertical parallel wall fires with buoyancy induced flow, Paper A26 presented at the Sixth International Symposium on Fire Safety Science, Poitiers July 5-9, 1999, accepted for publication in the Proceedings, Publication IAFSS.

15) COUTIN M., MOST J.M., DELICHATSIOS, M. A., DELICHATSIOS, M.D., ³Flame heights in wall fires: Effects of width, confinement and pyrolysis length, Paper A31 presented at the Sixth International Symposium on Fire Safety Science, Poitiers July 5-9, 1999, accepted for publication in the Proceedings, Publication IAFSS.

16) WANG H.Y., JOULAIN P., Numerical study of the turbulent burning between parallel walls with a fire induced flow, accepted for publication in Combustion Science and Technology, 1999.

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