Downward Flame Spread Under the Influence of Externally Applied Thermal Radiation

Abstract

Downward flame spread velocity over vertical sheets of polymethylmethacrylate (PMMA) and Filter Paper were measured under the influence of externally applied radiant fluxes ranging from 0 to 2.0 W/cm². The flame spread rate was found to be dependent primarily on the surface temperature of the fuel prior to flame arrival. A power law correlation exists between the flame spread velocity and the difference between the vaporization temperature of the fuel and its surface temperature in the region not affected by the heat transferred from the flame. Present theoretical models for downward flame spread were extended to account for the additional effect of external radiation. It is shown that the predictions of the theoretical models agree qualitatively with the experimental observations.