Experimental Study of Upward Flame Spread over Discrete Weathered Wood Chips

Wooden culture heritage has caused serious results due to the ravages of frequent fire disasters. The fire propagation over the weathered wood was reported to be fast, especially wood separated by air gaps. Presently, experiments were performed to study weathering effects on the flame spread performance over discrete wood chips separated by air gaps. A series of six 2 cm-long 10 cm-wide wood chips were uniformly installed on a vertical sample holder. The thickness of wood chips differed from 1 mm to 7 mm, the air gaps between the two samples varied from 1 cm to 2 cm. The flame spreads across or along with the woodgrain orientation. It indicates that the accelerated weathering process impacted a clear influence on flame spread over discrete wood chips. Regarding the flame spread across woodgrain orientation, both burning duration and MLR were reduced. In contrast, the burning duration was greatly enlarged but MLR was decreased when flame spread along with the woodgrain orientation. In general, the thickness differing from 3 mm to 7 mm was found to be linear with averaged flame spread rate. It suggests that the flame length of the samples with a horizontal grain orientation (flame across woodgrain) and vertical grain orientation (flame along with woodgrain) are increased and shorten greatly due to accelerated weathering, respectively.

Automated summary

Wooden cultural heritage has been seriously damaged by frequent fire disasters. Experiments show that weathering affects the flame spread performance between separated wood chips, with burning duration and MLR reduced when flames spread across the woodgrain orientation. Increased burning duration but decreased MLR were observed when flames spread along with the woodgrain orientation.