Upward Flame Spread along the Vertical Corner Walls (October 1993)

摘要

Flame spread behavior and the pyrolysis region spread characteristics along vertical corner walls were studied in detail with an automated infrared imaging temperature measurement technique (IR technique). The technique was recently developed for the measurement of transient pyrolysis temperature on both charring and non-charring materials. Temporal isotherms on PMMA samples were successfully obtained, from which the progress rate of the pyrolysis front was automatically deduced. It was found that the pyrolysis front shape was always M-shaped, i.e., no spread along the corner, and the maximum spread is in a few centimeters away from the corner. Understanding of the mechanism of the M-shape formation is important in developing a prediction model of the spread rate. Four possible mechanisms were identified and flame displacement effects are found to be the principal mechanism. Transient total heat flux distributions above the M-shape pyrolysis peak for a spreading fire were measured. Using these values, it was shown that the upward spread rate is predictable from simple, one-dimensional, thermal model.