Fire Safety Science Digital Archive

In the description of the characteristic volume of fire behavior, fire intensity I, rate of spread r, and flame length L, etc. all have their scientific definitions, while the bound between the fireline and the residual region of a fire scene is not yet scientifically defined. This paper tries to find out theoretically the basis for dividing the bound, to give the fireline thickness D a scientific definition, and to propose a method of quantitative calculation. According to the generality of fuels, the time-dependent curves of fuels combustion rate are utilized to work out a formula by experience. On the basis of defining scientifically the fireline thickness, the Byram's formula is corrected, and a new one for calculating the fire intensity of surface fire, i, e. 1=0. 788HWr, is presented. In this formula , H is the combustion value of fuels; the calculating method of the thermal current intensity J is ·given, and Jmax = I. 25 HWr/D the calculating formula of flame length is revised, and a new one L=O. 77 5?I is proposed. In the spreading process of the forest fire, when the time needed for getting over a fireline thickness is T, it is called residence time. It is given out in this paper the method for estimating and determining the rate of spread r and the residence time T in the combustor. And on this basis the characteristic volume (W, I, R, D, T, L and Jmax , etc. ) of surface fire behavior can be evaluated.