中空结构可燃物竖直向上火蔓延特性实验研究*

为探究中空结构固体可燃物竖直向上火蔓延的特征规律，针对不同试样内径(d)的瓦楞纸圆管进行竖直向上的火蔓延实验研究，探讨试样内径对其竖直向上火蔓延特性的影响。结果表明:其火蔓延过程可以分为火焰发展、稳定蔓延和火焰衰弱3个阶段，蔓延过程中对流换热占据主导地位；平均火焰高度随d的增大先增大后略微减小，在d=70 mm时达到最大；火蔓延速率和质量损失速率均随d的增大而增大，并且质量损失速率与d存在较好的线性关系；火蔓延速率与热释放速率呈现出较好的幂次关系。可以发现在一定范围内，中空结构可燃物的内径越大其火灾危险性越高。

Experimental study on vertical upward flame spread characteristics of combustible with hollow structure

In order to explore the characteristic laws of vertical upward flame spread of solid combustibles with hollow structures,a series of vertical upward flame spread tests were conducted aiming at the corrugated paper circular pipes with different inner diameters of specimen (d),and the influence of inner diameter of specimen on the characteristics of vertical upward flame spread was discussed.The results showed that the flame spread process could be divided into three stages: flame development,steady spread and flame decay,and the convective heat transfer played a dominant role in the flame spread process.The average flame height increased first and then decreased slightly with the increase of d,and reached the maximum when d=70 mm.Both the flame spread velocity and mass loss rate increased with the increase of d,and there was a good linear relationship between mass loss rate and d.There was a good power relationship between flame spread velocity and heat release rate.It could be found that within a certain range,the larger the inner diameter of combustible with hollow structure,the higher the fire risk.