FLAME SPREAD OVER COMBUSTIBLE SURFACES FOR LAMINAR-FLOW SYSTEMS .1. EXCESS FUEL AND HEAT-FLUX

The fire hazard of a combustible material may be ranked according to its ignition and flame spread characteristics. For chemically reacting flow systems, the spread rate assumes a special significance because the rate is usually faster than for stagnant systems. What fuel parameters significantly control the flame spread rate? In this paper, we focus our attention on the production of “excess fuel,” “excess flame length” due to burning of excess fuel, the heat fluxes to the burnt region and unburnt regions which raise the temperature of virgin surface to the gasification level, and finally the flame spread rate. In Part I, we have used integral techniques to obtain simple results for excess fuel and heat fluxes to the burning surface for buoyant, forced convection and stagnation flow systems; explicit but approximate results are provided for each parameter of interest and they are compared with numerical results and with experiment to provide a check on the present results. In Part II those results are utilized to obtain approximate but explicit expressions for excess flame length and flame spread rate in terms of known fuel and oxidizer properties. © 1979 G, Taylor & Francis Group, LLC. All rights reserved.