中文摘要：

以2cm厚硬质聚氨酯（RPU）保温板为研究对象，实验研究了试样宽度对竖向逆流燃烧蔓延过程中火焰高度、脉动频率、火焰温度及蔓延速度等特征参量的影响．结果表明，宽度一定时相关特征参量不随时间变化，随着宽度的增加，燃烧程度逐渐加剧，火焰脉动频率先增大后减小，平均火焰高度与火蔓延速度的变化趋势基本一致，均表现为先增大后减小，最终趋于不变，而气相火焰最高温度基本保持不变．

英文摘要：

A series of experiments were carried out to study the effect of sample width on downward flame spread. Samples used are 2 cm thick rigid polyurethane （RPU） slabs with the fixed height of 50 cm and varied widths. The variations of some important parameters, such as flame height, pulsation frequency, maximum gas flame temperature and flame spread rate, were measured and analyzed. Results show that when the width is fixed, the parameters mentioned above do not change with time. With the expansion of width, both average flame height and flame spread rate increase first and then decrease and finally reach a steady state, flame pulsation frequency increases first and then decreases since sample width is more than 20 cm, while maximum gas flame temperature remain almost unchanged.