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RESEARCH ARTICLE
Contents Vol 19(2)

Ignition and flame-growth modelling on realistic building and landscape objects in changing environments

Mark A. Dietenberger
+ Author Affiliations
- Author Affiliations

USDA Forest Service, Forest Products Laboratory, 1 Gifford Pinchot Drive, Madison, WI 53726, USA. Email: mdietenberger@fs.fed.us

International Journal of Wildland Fire 19(2) 228-237 https://doi.org/10.1071/WF07133
Submitted: 2 August 2007  Accepted: 22 May 2009   Published: 31 March 2010

Abstract

Effective mitigation of external fires on structures can be achieved flexibly, economically, and aesthetically by (1) preventing large-area ignition on structures by avoiding close proximity of burning vegetation; and (2) stopping flame travel from firebrands landing on combustible building objects. Using bench-scale and mid-scale fire tests to obtain flammability properties of common building constructions and landscaping plants, a model is being developed to use fast predictive methods suitable for changing environments imposed on a parcel lot consisting of structures and ornamental plants. Eventually, the property owners and associated professionals will be able to view various fire scenarios with the ability to select building materials and shapes as well as select ornamental plant species and their placement for achieving the desired fire mitigation. The mathematical formulation presented at the 2006 BCC Research Symposium is partially shown here and some results are compared with (1) specialised testing of Class B burning brands (ASTM E108) in the cone calorimeter (ASTM E1354); (2) our refurbished and modified Lateral Ignition and Flame Travel Test (ASTM E1321 and E1317); (3) room-corner tests with oriented-strand board (ISO 9705); and (4) cone calorimeter tests of fire-resistive materials such as fire retardant-treated plywood and single-layer stucco-coated oriented-strand board.

Additional keywords: calorimetry, fire mitigation, flammability modelling.


References


Babrauskas V (2003) ‘Ignition Handbook.’ (Fire Science Publishers: Issaquah, WA)

Dietenberger MA (1991) Piloted ignition and flame spread on composite solid fuels in extreme environments. PhD dissertation, University of Dayton, OH.

Dietenberger MA (1994) Protocol for ignitability, lateral flame spread, and heat release rate using LIFT apparatus. In ‘Fire and Polymers II. Materials and Tests for Hazard Prevention: Proceedings of 208th National Meeting of the American Chemical Society August 1994’, 21–26 August 1994, Washington, DC. (Ed. GL Nelson) ACS Symposium Series 599, Chapt. 29. (American Chemical Society: Washington, DC) Available at http://www.fpl.fs.fed.us/documnts/pdf1995/diete95c.pdf [Verified 3 March 2010]

Dietenberger MA (2004) Ignitability of materials in transitional heating regimes. In ‘Wood & Fire Safety: Proceedings, 5th International Scientific Conference’, 18–22 April 2004, Svolen, Slovakia. pp. 31–41. (Faculty of Wood Sciences and Technology, Technical University of Zvolen: Zvolen, Slovakia) Available at http://www.fpl.fs.fed.us/documnts/pdf2004/fpl_2004_dietenberger001.pdf [Verified 22 March 2010]

Dietenberger MA (2006a) Using a quasi-heat-pulse method to determine heat and moisture transfer properties for porous orthotropic wood products or cellular solid materials. Journal of Thermal Analysis and Calorimetry  83(1), 97–106.
| Crossref | GoogleScholarGoogle Scholar | CAS | Dietenberger MA (2006b) Analytical modeling of fire growth on fire-resistive wood-based materials with changing conditions. In ‘ Proceedings of the Conference on Recent Advances in Flame Retardancy of Polymeric Materials, Volume XVII: Applications, Research and Industrial Development Markets’, August 2006, Norwalk, CT. pp. 13–24. (BCC Research: Nowalk, CT) Available at http://www.fpl.fs.fed.us/documnts/pdf2006/fpl_2006_dietenberger002.pdf [Verified 3 March 2010]

Dietenberger MA, Grexa O (1999) Analytical model of flame spread in full-scale room/corner tests (ISO9705). In ‘Fire and Materials 1999 6th International Conference’ 22–23 February 1999, San Antonio, TX. (Eds M Janssens, S Grayson) (Interscience Communications Ltd: London) Available at http://www.fpl.fs.fed.us/documnts/pdf1999/diete99a.pdf [Verified 3 March 2010]

Karlsson B (1993) A mathematical model for calculating heat release rate in the room-corner test. Fire Safety Journal  20, 93–113.
| Crossref | GoogleScholarGoogle Scholar |

Manzello SL, Cleary TG, Shields JR , Yang JC (2006) On the ignition of fuel beds by firebrands. Fire and Materials  30, 77–87.
| Crossref | GoogleScholarGoogle Scholar | CAS |

White RH , Zipperer WC (2010) Testing and classification of individual plants for fire behaviour: plant selection for the wildland–urban interface. International Journal of Wildland Fire  19, 213–227.
| Crossref | GoogleScholarGoogle Scholar |




Nomenclature

  • αs = ϵs, surface absorptivity equal to surface emissivity for most building materials

  • δf, exponential decay with characteristic length for flame extension (m)

  • ϵf, flame emissivity

  • ωm, decay coefficient for material burn-off (1 s–1)

  • ρ, dry body density (kg m–3)

  • α = Kq/ρCq, thermal diffusivity (m2 s–1)

  • σ, Stefan–Boltzmann constant (kW K–4 m–2)

  • τm, material time constant (s)

  • Af, flame area on combustible object (m2)

  • Ap, combustible object pyrolysis area (m2)

  • Cq, heat capacity (kJ kg–1 K–1)

  • H(ti – t1), Heaviside function

  • hcf, flaming convective coefficient (kW m–1 K–1)

  • Qt, HRR, total heat release rate (kW)

  • Q″m,ig, material peak HRR flux (kW m–2)

  • Kq, thermal conductivity coefficient (kW m–1 K–1)

  • ℓ, material thickness (m)

  • WF07133_IE2.gif(ℓ, t) time stepping changes in surface heat fluxes (kW m–2)

  • WF07133_IE2.gif(0, t) time stepping changes in back-side heat fluxes (kW m–2)

  • WF07133_IE5.gif, irradiance (kW m–2)

  • WF07133_IE6.gif, imposed heat flux from ignition burner or the firebrand flame and glow (kW m–2)

  • si, growth acceleration coefficients (Eqn 15)

  • WF07133_IE4.gif, series expansion solution (Eqn 2)

  • t, current time (s)

  • WF07133_IE1.gif, temperature change (K)

  • Tf, averaged measured flame temperature (K)

  • Tig, ignition temperature (K)

  • vp, quasi-steady speed of surface flame spread (m s–1)

  • w, flame width (m)

  • WF07133_IE3.gif, dimensional depth (m)

  • y, surface distance (m)