不同宽度及放置角度下聚甲基丙烯酸甲酯的燃烧传热特性

Effects of Width and Incline Angle on Combustion and Heat Transfer Characteristics of Poly(methyl methacrylate)

研究了宽度分别为2 cm、3 cm、5 cm和8 cm的聚甲基丙烯酸甲酯(PMMA)在放置角度为0°、15°、30°和45°的情况下燃烧传热特性。通过图像分析、红外热像、热电偶测温等技术对火焰形态及燃烧特性参数(火蔓延速度、火焰倾角、火焰高度以及火焰温度等)进行了表征。研究发现,有机玻璃燃烧过程中,热解前锋呈现出U型的特点,宽度越大,其U型演变时间越长。放置角度越大时,火蔓延速度对宽度的敏感性越大,即宽度越大火蔓延速度越大。这主要由于,随着宽度和放置角度的增加,火焰倾角变得越来越小,火焰与材料表面更加贴近,从而促进热量的传递。研究同样发现,在相同放置角度下,平均火蔓延速度受平均火焰高度以及上下波动程度的影响;火焰温度基本上不受宽度影响等特点。

A serious of experiments were carried out on poly（methyl methacrylate） （PMMA） samples with the width of 2 cm, 3 cm, 5 cm and 8 cm inclined at the angles of 0°,15°,30° and 45°, respectively. The flame structure and combustion parameters such as： flame spread speed, flame angle, flame height and flame temperature were investigated by image analysis, infrared thermography and thermocouple etc. It is found that, during the flame spread process, the pyrolysis front shows a U shape. With increase of the width, the revolution of U shape will take much more time. Meanwhile, the flame spread speed is greatly influenced by width at the larger incline angle, which means the wider PMMA samples will have larger flame spread speed. It can be attributed to that, with increase of the width and incline angle, the flame angle will become smaller making the flame close to the surface, and therefore promoting the heat transfer. It is also found that, the average flame spread speed is influenced by the average flame height and fluctuation and, the flame temperature doesn’t change with width at the same incline angle.