A dimensionless correlation for the spread of wind-driven fires

Abstract

Data for the behavior of 59 experimental wind-driven fires were extracted from the literature for use in determining a correlation among several variables known to influence the rate of forest fire spread. Also included in the correlation were unpublished data from six field fires. This information consisted of behavior measurements on small-scale burns of artificial fuels in the laboratory and measurements on field fires in diverse fuels such as grass and logging slash. Fire intensities ranged from about 40 to 4600 kW/m. Dimensional analysis was used to derive three variables governing the fire spread process. These variables, rearranged into a dimensionless rate of spread and a dimensionless wind speed, are strongly correlated and lead to a simple expression for fire spread rate in terms of fuel consumption, ambient wind speed, and flame residence time.