Abstract: Abstract: Straw is a typical common combustible that may cause wildfires. The combustion process of naturally cumulated is necessary to be studied. In this paper, the combustion experiments of cylindrical straw were carried out. The diameters were 60 cm and 90 cm, and the thicknesses were from 2.94 cm to 12.23 cm. The combustion process of straw under different conditions were compared, and the parameters of combustion characteristics such as the mass loss rate and flame temperature were analyzed. The results show that the straw combustion process can be divided into four stages, including initial central stage, merged annular stage, separated annular stage, and decay stage. The mass loss rate has an excellent linear relationship with the thickness of straw. And a larger diameter would cause a larger mass loss rate as well. The flame temperature presents a trend of “increase rapidly-decrease slowly” via time. The flame axis temperature decreases gradually with the elevated height, which is close to 800 ℃ near the straw surface and lower than 200 ℃ at the height of 0.9 m. The conclusions benefit to deepen the understanding of the development and spread process and characteristics of straw fire.

Key words: Key words: straw, cumulated dimensions, combustion characteristics, flame temperature, mass loss rate