Upward flame spread on vertical walls with external radiation.

摘要

In enclosure fires, the interaction of burning walls supplying radiation to other walls can significantly enhance the fire hazard by causing sustained flame spread on materials that do not allow flame spread without the aid of external radiation and more rapid spread rates. In the present study, external radiation was incorporated into the upward flame experiments and theoretical/numerical model to thoroughly examine the effect on upward flame spread.;The current investigation entailed primarily an experimental look at the upward flame spread problem. A test facility was designed which could burn 1.2 m high by 0.3 m wide samples at moderate levels of external radiation (0-15 kW/m;The upward flame spread results confirmed that above a certain critical flux level, many materials do exhibit sustained upward flame spread; and these critical levels were determined for the materials tested. Also, higher flux levels enhanced the flame spread rate and quantitative flame spread information was measured.;A small-scale test apparatus was used to measure the mass loss rate of the test materials at several levels of external radiation. The mass loss rate data was used as an input for the numerical model.;A previously developed numerical model was modified to take into account the effect of external radiation. The model employed finite difference equations to solve the two-dimensional, transient heat conduction equation for the solid sample. Time- and space-dependent heat feedback to the sample surface, transient mass loss rate, established correlation for flame height, and established criteria for ignition were some of the concepts used in the model. The model correctly predicted the trends seen in the experimental data.