Critical phenomenon in compartment fires with liquid fuels

The objective of this paper was to analyze in detail the behaviour of liquid-fuel compartment fires and to present precise information on the whole aspect of the fire phenomenon for use in modelling compartment fires. Two hundred experiments were conducted to research the behaviour of liquid-fuel compartment fires as a function of the ventilation parameter A H and compartment size, where A is the area of the ventilation opening and H is its height. Especially the influence of the compartment on the burning behaviour was investigated, using various size compartments, and the total aspect of this influence was presented. A critical phenomenon was observed for a pertinent condition of the ratio of compartment size to fuel tray size. This phenomenon, which is closely associated with the enhancement of burning rate and oscillatory combustion, may be substantially controlled by the dynamic equilibrium between the rate of fuel gas supply and the rate of air supplied by ventilation. A maximum burning rate may be obtained at an extreme value on this equilibrium. For methanol pool fires, the maximum burning rate was up to 7.2 times the open burning rate. The temperature within the compartment near the maximum burning condition was unexpectedly uniform and isothermal, due to fluctuation of turbulent flames and recirculation of gas. These experimental results were compared with previous research in detailed discussion.