The Influence of the Coanda Effect on Flame Attachment to Slopes and Firefighter Safety Zone Considerations

摘要

The Coanda effect is the phenomenon in which a jet entering quiescent fluid attaches to a nearby solid object due to inhibited entrainment of ambient fluid near the solid. Little is known about the influence of the Coanda effect on wildland fire behavior. Specifically, there is a lack of knowledge regarding how the Coanda effect influences firefighter safety zone considerations in rugged terrain. This paper presents results for small-scale bum experiments testing the effect of slope angle, slope boundary condition and distance from flame base. There are three main conclusions based on the experiments performed herein: (1) for most of the flame characteristics examined, there is no difference between a bare slope and an insulated slope, (2) the average angle at which the deviation occurred is between 20° and 40°, depending on the criteria used, and (3) the traditional view of safe separation distance as being the distance from the flame base is inadequate for fires near slopes.