Laboratory facility for wind-aided firespread along a fuel matrix

Urban and wildland fires propagate via ignition of discrete fuel elements. Transfer of heat from burning to nonburning fuel is strongly influenced by wind because of its effects on combustion rates, on convective flow patterns, and on radiative transfer owing to its modification of the shape and ori...

Full description

Saved in:
Bibliographic Details
Published in:Combustion and flame 1984-01, Vol.57 (3), p.289-311
Main Authors: Fleeter, R.D., Fendell, F.E., Cohen, L.M., Gat, N., Witte, A.B.
Format: Article
Language:English
Subjects:
Applied sciences
Combustion of solid fuels
Combustion. Flame
Energy
Energy. Thermal use of fuels
Exact sciences and technology
Theoretical studies. Data and constants. Metering
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Urban and wildland fires propagate via ignition of discrete fuel elements. Transfer of heat from burning to nonburning fuel is strongly influenced by wind because of its effects on combustion rates, on convective flow patterns, and on radiative transfer owing to its modification of the shape and orientation of the thermal plume. Development of a large low-speed wind tunnel designed expressly for modeling wind-aided firespread, and results of preliminary tests, are described. The tunnel, capable of producing air velocities up to 20 m/s, has a test section of 1.12 × 1.12-m 2 cross section and 5-m length. A movable ceiling panel allows the plume to rise freely under buoyancy, and affords constant speed for the airflow approaching the propagating flamefront. The plume rises into a straight duct extending 3 m above the fuel matrix. Tests have been carried out with hardwood fuel at loadings of 0.32 and 4.8 kg/m 2 with air velocity 1.4 m/s. Fuel elements for the tests had total masses of 56.8 and 1500 mg, respectively. Steady-state flame propagation was achieved for the lower fuel loading, with a flame width of 1 m. The 4.8 kg/m 2 loading did not achieve steady state, and the burning-zone width increased to the entire length of the test section. This difference is attributed to the larger time required to burn the more massive fuel elements. In both cases the propagation was most rapid along the center of the matrix; in the lower-loading case, some unburned fuel remained at the sides of the matrix, possibly as the result of diminished heat transfer to these elements, as well as of radiative losses to the walls. Flame-propagation-rate data from video and thermocouple data for the two cases are compared. Observations of backflow downwind of the flamefront and of plume rise angle are discussed.
ISSN:0010-2180
1556-2921
DOI:10.1016/0010-2180(84)90049-X