Cellular and turbulent ceiling fires

Abstract

Large scale ceiling fires are characterized by cellular and turbulent flames. The chemical and physical scaling laws governing such flows are obtained through a theory based on turbulent free convective heat transfer measurements. It is shown that the dimensionless burning rate is essentially controlled by the B number, which characterizes liquid and solid fuels. The burning rate per unit area appears to be independent of both the surface area of the ceiling and the depth of the flaming zone. A parallel experimental study is presented in which solid and liquid fuels are simulated with gaseous fuel inert mixtures flowing through sintered metal burners. Good agreement between theory and experiment is found for all experimentally varied chemical and physical parameters, which include ceiling size, fuel mixture supply rates, fuel-inert mass fractions, and fuel molecular weights. The accompanying paper shows that turbulent pool fires can be described by a closely related burning model.