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.

摘要

木质文化遗产因火灾频发，造成严重后果。据报道，风化木材上的火势传播速度很快，尤其是被气隙隔开的木材。目前，进行了实验以研究风化对由气隙隔开的离散木片的火焰传播性能的影响。一系列 6 个 2 cm 长 10 cm 宽的木片均匀地安装在垂直样品架上。木片的厚度从 1 毫米到 7 毫米不等，两个样品之间的气隙从 1 厘米到 2 厘米不等。火焰在木纹方向上或沿着木纹方向蔓延。这表明加速风化过程对火焰在离散木片上的蔓延产生了明显的影响。关于在木纹方向上蔓延的火焰，燃烧持续时间和 MLR 都减少了。相比之下，当火焰随着木纹方向蔓延时，燃烧持续时间大大延长，但MLR降低。一般来说，发现从 3 毫米到 7 毫米的厚度与平均火焰蔓延速率呈线性关系。这表明，由于加速风化，具有水平纹理取向（火焰穿过木纹）和垂直纹理取向（火焰伴随木纹）的样品的火焰长度分别大大增加和缩短。