A review of radiant heat flux models used in bushfire applications

The need to determine the radiant heat flux (RHF) from bushfires for fire behaviour prediction, firefighter safety, or building protection planning purposes has lead to the development and implementation of a number of RHF models, most of which are based on the Stefan-Boltzmann equation of radiative heat transfer. However, because of the complex nature of bushfire flames, a number of assumptions are made in order to make the implementation of the radiative heat transfer equation practical for wildland fire applications. The main assumptions are: bushfire flame characteristics (geometry, temperature), flame radiative qualities (emission type, emissivity), and the view of the flame at the receiving element. The common assumption of a uniform emissivity of unity and an isothermal rectangular emitting surface produces a generic RHF model described here as an 'opaque box'. Because of the broad assumptions inherent in the opaque box model, it predicts the RHF of bushfires poorly. A comparison is made between the generic opaque box RHF model and the measurements of radiant heat flux emitted by a stationary propane-fuelled artificial bushfire flame front. Knowledge about the geometry and an understanding of the flame characteristics of a bushfire front are needed before generic RHF models will adequately describe the RHF emitted from bushfire flames.

[1]  J. D. Walker,et al.  Thermocouple errors in forest fire research , 1968 .

[2]  Bret W. Butler,et al.  Firefighter Safety Zones: A Theoretical Model Based on Radiative Heating , 1998 .

[3]  J.-L Dupuy.  Testing Two Radiative Physical Models for Fire Spread Through Porous Forest Fuel Beds , 2000 .

[4]  E. A. Catchpole,et al.  Uniform Propagation of a Planar Fire Front Without Wind , 1989 .

[5]  F. Albini.  A Model for Fire Spread in Wildland Fuels by-Radiation† , 1985 .

[6]  L. McCaw,et al.  The Dead-Man Zone—a neglected area of firefighter safety , 2001 .

[7]  E. Whittaker.  TEMPERATURES IN HEATH FIRES , 1961 .

[8]  J. Winkel,et al.  Infrared Measurements of Energy Release and Flame Temperatures of Forest Fires , 1998 .

[9]  D. Hird,et al.  A PHOTOMETRIC METHOD OF DETERMINING CONFIGURATION FACTORS , 1953 .

[10]  E. Johnson,et al.  Forest fire behavior , 1992 .

[11]  J. H. McGuire,et al.  Heat Transfer by Radiation , 1954, Nature.

[12]  D. X. Viegas,et al.  Criteria for determining the safe separation between structures and wildlands. , 2002 .

[13]  J. Gore,et al.  RADIATION FROM TURBULENT DIFFUSION FLAMES , 1989 .

[14]  E. Sparrow,et al.  Radiation Heat Transfer , 1978 .

[15]  William H. Frandsen,et al.  Fire spread through porous fuels from the conservation of energy , 1971 .

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

[17]  Y. Jaluria,et al.  An Introduction to Heat Transfer , 1950 .

[18]  R. Weber,et al.  Analytical models for fire spread due to radiation , 1989 .

[19]  Andrew L. Sullivan,et al.  Predicting the radiant heat flux from burning logs in a forest following a fire , 2002 .

[20]  J. Balbi,et al.  Dynamic modelling of fire spread across a fuel bed , 1999 .