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Modeling of Enclosure Fires.

PB90129867

Publication Date	1972
Personal Author	Heskestad, G.
Page Count	32
Abstract	A proposal was made for an approximate modeling technique for enclosure fires based on the hypothesis that the combustion of a fuel pile in an enclosure depended on associated differences in the fluid mechanical properties and the chemical composition of the gas supply to the fire. Earlier work concerning unconfined fires of wood cribs was reviewed. Under the assumption of large Grashof numbers for the convective flow, application of the modeling hypothesis resulted in the following sufficiency conditions for predicting fire properties on one enclosure scale from experiments on another scale: the enclosures must be geometrically similar; unconfined burning rates of the fuel piles in the two enclosures must be in the ratio of the linear scale ratio to the 5/2 power; porosities of the fuel piles must be conserved from one scale to the other; and the thermal properties of the walls must be modeled for proper thermal response. The third and fourth conditions were not satisfied by experiments available for testing the modeling technique. However, data on burning rates, selected gas species and overall fire behavior conformed well with the modeling hypothesis. Probably due to the fact that wall properties had not been modeled, temperatures did not conform.
Keywords	Fires Models Enclosures Fire hazards Fire safety Fire tests Mathematical models Combustion Porosity Fuels Grashof number
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	89G - Construction Materials, Components, & Equipment
Corporate Authors	Factory Mutual Research Corp., Norwood, MA.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Presented at the International Symposium on Combustion (14th), University Park, PA., August 1972. Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199004

Modeling of Enclosure Fires.

Modeling of Enclosure Fires.
PB90129867

Publication Date	1972
Personal Author	Heskestad, G.
Page Count	32
Abstract	A proposal was made for an approximate modeling technique for enclosure fires based on the hypothesis that the combustion of a fuel pile in an enclosure depended on associated differences in the fluid mechanical properties and the chemical composition of the gas supply to the fire. Earlier work concerning unconfined fires of wood cribs was reviewed. Under the assumption of large Grashof numbers for the convective flow, application of the modeling hypothesis resulted in the following sufficiency conditions for predicting fire properties on one enclosure scale from experiments on another scale: the enclosures must be geometrically similar; unconfined burning rates of the fuel piles in the two enclosures must be in the ratio of the linear scale ratio to the 5/2 power; porosities of the fuel piles must be conserved from one scale to the other; and the thermal properties of the walls must be modeled for proper thermal response. The third and fourth conditions were not satisfied by experiments available for testing the modeling technique. However, data on burning rates, selected gas species and overall fire behavior conformed well with the modeling hypothesis. Probably due to the fact that wall properties had not been modeled, temperatures did not conform.
Keywords	Fires Models Enclosures Fire hazards Fire safety Fire tests Mathematical models Combustion Porosity Fuels Grashof number
Source Agency	National Institute for Occupational Safety and Health
NTIS Subject Category	89G - Construction Materials, Components, & Equipment
Corporate Authors	Factory Mutual Research Corp., Norwood, MA.; National Inst. for Occupational Safety and Health, Cincinnati, OH.
Supplemental Notes	Presented at the International Symposium on Combustion (14th), University Park, PA., August 1972. Sponsored by National Inst. for Occupational Safety and Health, Cincinnati, OH.
Document Type	Technical Report
NTIS Issue Number	199004