The effects of slope and fuel bed width on laboratory fire behaviour

A set of 109 laboratory fires in Pinus halepensis fuel beds (1 kg m–2) was used to test the effects of slope (0°, 10°, 20°, 30°) and fuel bed width (1, 2, 3 m) on fire behaviour variables such as rate of spread, fuel consumption, flame residence time, temperatures and flame geometry. The qualitative behaviour of the fires is also reported. The 20° and 30° upslope fires are pointed in shape and fire whirls moving along the fire flanks in the direction of the fire head are systematically observed in 30° upslope fires. Flame residence time increases with increasing slope angle, and both slope angle and fuel bed width affect rate of spread. The slope effects observed in 10° and 20° slope angles and in the narrowest fuel beds (1 and 2 m) are similar to those predicted by operational models. However, the observed slope effect at the 30° slope angle is underestimated by these models, in particular in 3 m-wide fuel beds. Flame temperatures correlate closely with dimensionless height and flame lengths correlate closely with fire line intensity. Mechanisms that could explain the different effects observed are suggested and discussed.

[1]  Gregory S. Biging,et al.  A Qualitative Comparison of Fire Spread Models Incorporating Wind and Slope Effects , 1997, Forest Science.

[2]  Dougal Drysdale,et al.  Flame spread on inclined surfaces , 1992 .

[3]  J. Dupuy,et al.  Slope effect on laboratory fire spread: contribution of radiation and convection to fuel bed preheating , 2011 .

[4]  D. Drysdale.  An Introduction to Fire Dynamics , 2011 .

[5]  Francisco Rego,et al.  Empirical modelling of surface fire behaviour in maritime pine stands , 2009 .

[6]  R. M. Nelson.  An effective wind speed for models of fire spread , 2002 .

[7]  J.M.P. Ventura,et al.  Flame characteristics in fires propagating in beds of Pinus halepensis needles , 2006 .

[8]  Ian R. Noble,et al.  McArthur's fire-danger meters expressed as equations , 1980 .

[9]  Begoña C. Arrue,et al.  Analysis of fire behaviour in Mediterranean shrubs: The Gestosa fire experiments (Portugal) , 2006 .

[10]  Albert Simeoni,et al.  Fire spread across pine needle fuel beds: characterization of temperature and velocity distributions within the fire plume , 2004 .

[11]  Carl W. Adkins,et al.  A dimensionless correlation for the spread of wind-driven fires , 1988 .

[12]  Dougal Drysdale,et al.  Fire driven flow in an inclined trench , 1995 .

[13]  Tom Beer,et al.  The interaction of wind and fire , 1991 .

[14]  J. Dupuy,et al.  Mieux comprendre et prédire la propagation des feux de fôrets : expérimentation, test et proposition de modèles , 1997 .

[15]  Paul-Antoine Santoni,et al.  The contribution of radiant heat transfer to laboratory-scale fire spread under the influences of wind and slope , 2001 .

[16]  Jason J. Sharples,et al.  Review of formal methodologies for wind–slope correction of wildfire rate of spread , 2008 .

[17]  R. McAlpine,et al.  The effect of fire front width on surface fire behaviour , 1999 .

[18]  G. M. Byram,et al.  The modeling of fire whirlwinds. , 1970 .

[19]  Jean-Luc Dupuy,et al.  Slope and Fuel Load Effects on Fire Behavior: Laboratory Experiments in Pine Needles Fuel Beds , 1995 .

[20]  Jr. Ralph M. Nelson,et al.  Reaction times and burning rates for wind tunnel headfires , 2003 .

[21]  J. Dupuy,et al.  Fires from a cylindrical forest fuel burner: combustion dynamics and flame properties , 2003 .

[22]  José M. C. Mendes-Lopes,et al.  Flame characteristics, temperature-time curves, and rate of spread in fires propagating in a bed of Pinus pinaster needles , 2003 .

[23]  J. Dupuy,et al.  Thermal infrared emission–transmission measurements in flames from a cylindrical forest fuel burner , 2007 .

[24]  Jon D. Johnson.  A rapid technique for estimating total surface area of pine needles. , 1984 .

[25]  Domingos Xavier Viegas,et al.  Fire line rotation as a mechanism for fire spread on a uniform slope , 2002 .

[26]  N. Cheney,et al.  The Influence of Fuel, Weather and Fire Shape Variables on Fire-Spread in Grasslands , 1993 .

[27]  F. Albini,et al.  A model for the wind-blown flame from a line fire , 1981 .

[28]  Carl W. Adkins,et al.  Flame characteristics of wind-driven surface fires , 1986 .

[29]  Domingos Xavier Viegas,et al.  Parametric study of an eruptive fire behaviour model , 2006 .