Fire Safety Science Digital Archive

An experimental investigation is conducted to study the effect of sample orientation on piloted ignition and opposed-wind flame spread. Two types of wood (red oak and mahogany) were used for the purpose and two orientations (horizontal and vertical) were investigated. In the horizontal mode, axisymmetric fire spread over wood samples was studied and the corresponding piloted ignition tests were conducted on smaller samples of the same wood. In the vertical mode, lateral flame spread and piloted ignition tests were conducted in a radiant panel test apparatus. The experimental data were reduced according to the thermal flame spread theory of deRis using the measured surface temperatures. It was found that as long as the temperatures are defined consistently with the thermal theory, the results are orientation independent within the measurement error. The reasons for this orientation independence are: (i) dominant re-radiative losses, and (ii) insensitivity of the flame spread rate to the induced air velocity at ambient 02 concentrations.