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Characterization of convective heating in full scale wildland fires

Author(s): Bret W. Butler
Editor(s): Domingos Xavier Viegas
Year Published: 2010

Data collected in the International Crown Fire modeling Experiment during 1999 are evaluated to characterize the magnitude and duration of convective energy heating in full scale crown fires. To accomplish this objective data on total and radiant incident heat flux, air temperature, and horizontal and vertical gas velocities were evaluated. Total and radiant energy fluxes were measured. Temperatures were measured using bare Type K 0.13 mm wire diameter thermocouples. Gas velocities were measured using pitot-static type sensors designed specifically for velocity measurements in fires. The experiments occurred in 14 m tall jack pine stands. Flames were 18-25 m tall, fire spread rates were between 0.5 and 1.0 m-s-1. The magnitudes of the temperatures presented are representative of those found in naturally occurring wildland fires. The measured peak gas temperatures varied from 1000 to 2000 K, and gas velocities of 10 to 20 m-s-1. Convective heating rates reached 150 kW-m-2 for short durations (5 to 10 seconds) with sustained flux rates of 40 to 80 kW-m-2 for durations of (~20 to 40 s). The data suggest that maximum convective heat transfer coefficients to the sensor face range from 30 to 50 W-m-2-K-1.

Citation: Butler, B. W. 2010. Characterization of convective heating in full scale wildland fires. In: Viegas, D. X., ed. Proceedings of the VI International Conference on Forest Fire Research; 15-18 November 2010; Coimbra, Portugal. Coimbra, Portugal: University of Coimbra. 9 p.
Topic(s): Fire Behavior, Data Evaluation or Data Analysis for Fire Modeling, Extreme Fire Behavior, Fuels, Fuel Treatments & Effects, Naturally-ignited Fire-use treatments
Ecosystem(s): None
Document Type: Conference Proceedings
NRFSN number: 16929
Record updated: Jul 6, 2018