Experimental Study of Upward Flame Spread over Discrete Weathered Wood Chips

ABSTRACT

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.

KEYWORDS:

• Discrete fuels
• flame spread rate
• MLR
• weathered wood
• wooden culture heritage

Acknowledgments

The authors gratefully acknowledge Dr.Yoshioka Hideki (Building Research Institute of Japan) for providing the cedar specimens.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by “the Fundamental Research Funds for the Central Universities” No. 2020XJAQ03. This work was supported by the National Key R&D Program of China No. 2018YFC0807600.