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Measurements of convective and radiative heating in wildland fires

Author(s): David Frankman, Brent W. Webb, Bret W. Butler, Daniel M. Jimenez, Jason M. Forthofer, Paul Sopko, Kyle S. Shannon, J. Kevin Hiers, Roger D. Ottmar
Year Published: 2012
Description:

Time-resolved irradiance and convective heating and cooling of fast-response thermopile sensors were measured in 13 natural and prescribed wildland fires under a variety of fuel and ambient conditions. It was shown that a sensor exposed to the fire environment was subject to rapid fluctuations of convective transfer whereas irradiance measured by a windowed sensor was much less variable in time, increasing nearly monotonically with the approach of the flame front and largely declining with its passage. Irradiance beneath two crown fires peaked at 200 and 300 kW m^-2, peak irradiance associated with fires in surface fuels reached 100 kW m^-2 and the peak for three instances of burning in shrub fuels was 132 kW m^-2. The fire radiative energy accounted for 79% of the variance in fuel consumption. Convective heating at the sensor surface varied from 15% to values exceeding the radiative flux. Detailed measurements of convective and radiative heating rates in wildland fires are presented. Results indicate that the relative contribution of each to total energy release is dependent on fuel and environment.

Citation: Frankman, David; Webb, Brent W.; Butler, Bret W.; Jimenez, Daniel; Forthofer, Jason M.; Sopko, Paul; Shannon, Kyle S.; Hiers, J. Kevin; Ottmar, Roger D. 2012. Measurements of convective and radiative heating in wildland fires. International Journal of Wildland Fire. 22(2): 157-167.
Topic(s): Fire Effects, Ecological - First Order, Fire Severity
Ecosystem(s): Montane wet mixed-conifer forest, Montane dry mixed-conifer forest, Ponderosa pine woodland/savanna, Mountain shrubland/wooded draw, Sagebrush steppe, Lower montane/foothills/valley grassland
Document Type: Book or Chapter or Journal Article
NRFSN number: 8374
FRAMES RCS number: 13442
Record updated: Apr 20, 2017