中文摘要：

利用红外热像技术，对受限空间内热塑性材料熔融燃烧过程中初始发展阶段的固体样品表面的二维火蔓延速率进行了实验研究，分析样品与其下部油盆的间距对样品表面火蔓延速率的影响．在ISO9705燃烧室内，针对6mm厚聚丙烯板，考虑了0cm、5cm、10cm、15cm、25cm和35cm共6种不同间距，开展了6组全尺寸火灾实验，记录了样品表面的温度场数据，得到了样品表面火蔓延速率的变化规律．结果表明，由于液体油池火的影响，固体表面二维火蔓延速率随时间呈指数增长关系，且其增长速率随间距的增加而降低．

英文摘要：

The objective of this paper is to investigate the two-dimensional fire spread speed of thermoplastics in enclosure based on infrared thermal image during the initial growth period. Six large-scale fire tests of polypropylene （PP） sheets with a thickness of 6 mm were conducted in the ISO 9705 room, with the distance between the bottom of sample and the floor being 0 cm, 5 cm, 10 cm, 15 cm, 25 cm and 35 cm, respectively. The temperature fields of sample surface were recorded, and the fire spread speeds of sample surface were obtained. The results show that the two-dimensional fire spread speed of sample surface increases with time as an exponential function, and the increasing rate of fire spread speed decreases with the increase of distance.