BRE FN6 PDF

Recent engineering applications of theories of upward flame spread have used empirical data to describe the connection between the gas and solid phases, in particular the level and distribution of the rate of the transfer from the gas to the solid. At its simplest this approach requires a mean net heat flux to be given over the length of the flame ahead of the pyrolysing zone. Over this distance an output of heat release per unit area is specified.This Fire Note comments on the difference between a linear law concerning flame length and heat release and the more conventional 2/3 power law. It explores some variations in the simple thermal model of upward flame spread (one assuming the heat release rate per unit area is constant between the ignition time and the burn out time), and uses it to examine the role of sideways spread.