摘要：In this paper, a series of burning experiments with the downward fire spread were carried out using 1 mm thick, 200 mm tall PMMA with different widths varying from 50 mm to 150 mm in 13 mm restricted distance. The fire propagation parameters were observed and analyzed, including flame shape, pyrolysis front, pyrolysis length, flame height, and fire spread rate. The major conclusions are summarized as follows: The trends of the pyrolysis fronts and pyrolysis lengths with different widths show the increasing development under the limited condition. The flame height increase linearly as a function of time with the largest increase in 150 mm, followed by 100 mm and 50 mm. The wider the sample width, the faster the flame spread rate, Moreover, flame spread rate and flame width are exponentially related under constrained conditions, and the flame spread rate is proportional to the flame width with power value of 0.24 lowering than 0.5 and 0.35 in unlimited distance. The phenomenon is due to limited distance in this paper, and the flame spread rate of thermal thin materials is mainly affected by net heat flux. The conclusions of the study are meaningful for fire protection and fire development mechanisms.
关键词：Downward fire spread ; Flame height ; Pyrolysis front ; Flame spread rate
