Fire line rotation as a mechanism for fire spread on a uniform slope

Abstract

The evolution of a linear flame front in a homogeneous fuel bed in a slope, for arbitrary values of the initial orientation of the fire front is studied. It is shown that, with the exception of initially horizontal or down-slope propagating fire lines, the propagation is not stationary. In its movement the fire front rotates, tending to become parallel to the slope gradient direction. The concept of fire line rotation as a tool to interpret and describe the evolution of a fire front is presented. Experimental results developed at a laboratory scale in a 30˚ slope are presented to support it. Some insight about the role played by natural convection induced by the fire is provided. A model using the concept of fire line rotation is proposed to predict the evolution of a fire front. Its application to the case of a point ignition fire in a slope is presented.