Flame Characteristics Adjacent to a Stationary Line Fire

ABSTRACT

Thermocouples were used to measure gas temperatures as a function of distance to the edge of a rectangular burner. Experiments varied the energy release rate, burner aspect ratio, wind speed, and surface inclination angles. Mean gas temperature was nearly constant over the distance that flames attached to the down-wind or uphill surface. Beyond this region, mean temperature profiles declined as a power-function of distance, primarily due to increasing intermittency of flame impingement. A linear regression model characterized the power-law temperature profile and flame intermittency. The models were found to agree with measurements taken from spreading fires in laboratory and field experiments and suggest general scalability of predictions for characterizing convective heat transfer ahead of linear flame zones in wildland fires.

KEYWORDS:

• Flame
• wildfire
• temperature profile
• flame Intermittency
• gas Burner

Nomenclature and Units

Table

Acknowledgments

This study was funded by the USDA Forest Service, National Fire Decision Support Center. The authors acknowledge Randy Pryhorocki and Josh Deering for constructing the burner apparatus, and Grant Pearce and Tara Strand from SCION in New Zealand for organizing the crop stubble experiments. Andrew Gorris and Jon Bergroos worked tirelessly on thermocouple fabrication and maintenance. Evan Sluder and Mike Heck from University of Maryland, Fire Protection Engineering Department assisted with data collection and operating the experiments. The findings and conclusions in this paper are those of the authors and should not be construed to represent any official USDA or U.S. Government determination or policy.