Buoyant-flow downward flame spread over carbon fiber reinforced plastic in variable oxygen atmospheres
Buoyant-flow downward flame spread over carbon fiber reinforced plastic in variable oxygen atmospheres
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DOI：
10.1016/j.combustflame.2021.111528
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发表时间：
2021-06-13
影响因子：
4.4
通讯作者：
Takahashi, Shuhei
中科院分区：
文献类型：
--
作者：
Kobayashi, Yoshinari;Oiwa, Rikiya;Takahashi, Shuhei
本文研究了不同氧浓度下浮力流动下火焰在碳纤维增强塑料（CFRP）薄板上的向下蔓延。用浸渍环氧树脂的两种单向碳纤维（CF）片材复合，在高温炉中固化制成CFRP片材。制造的CFRP片材在允许氧气浓度变化的手套箱中燃烧。环氧树脂板也进行了试验，以研究碳纤维的影响。燃烧和未燃烧CFRP片材的SEM图像表明，火焰在CFRP片材上的蔓延是由浸渍环氧树脂的热解驱动的。CFRP片材的极限氧浓度（LOC）为31%，环氧树脂片材的极限氧浓度为19%。不同的热惯性会产生不同的可燃性。与可燃性顺序相反，CFRP片材的火焰蔓延率高于环氧树脂片材的31%以上。通过红外摄像机观察到的平面内温度分布表明，CFs将火焰的热量向前传导，从而加速了火焰的传播。换句话说，CFs充当热导体，就像电线火灾中的金属芯一样。为了预测碳纤维布的火焰传播行为，本文建立了一种新的简化的火焰传播模型，其中包括固相传热。根据模拟的表面温度分布模型，推导出各区域的能量平衡，推导出火焰蔓延速率的解析解。将计算得到的火焰蔓延速率与实测值进行比较，发现两者在数量上是一致的。该模型适用于其他热薄的高导热材料以及碳纤维增强玻璃钢片材，因此有助于此类材料的火灾风险评估。(C) 2021燃烧研究所。Elsevier Inc.出版。版权所有。
This study explored the downward flame spread over carbon fiber reinforced plastic (CFRP) sheets under buoyant flow in variable oxygen concentrations. Tested CFRP sheets were fabricated by laminating two unidirectional carbon fiber (CF) sheets impregnated with epoxy resins and curing them in a high-temperature furnace. The fabricated CFRP sheets were combusted in a glovebox which allowed oxygen concentration to vary. Epoxy resin sheets were also tested to investigate the effect of CFs. SEM images of burned and unburned CFRP sheets showed that the flame spread over the CFRP sheets was driven via the pyrolysis of the impregnated epoxy resins. The limiting oxygen concentration (LOC) of the CFRP sheets was 31%, while that of the epoxy resin sheets was 19%. The difference in flammability would be produced by the different thermal inertia. Contrary to the order of flammability, the flame spread rate of the CFRP sheets was higher than that of the epoxy resin sheets in more than 31% 0 2 . In-plane temperature distributions visualized via an IR camera suggested that the CFs conductively transferred heat from flame forward, thereby accelerating the flame spread. In other words, the CFs acted as heat conductors, such as metal cores in electrical wire fires. To predict the flame spread behaviors of the CFRP sheets, this work developed a novel simplified flame spread model that involves solid-phase heat transfer. According to the model with a simulated surface temperature profile, the analytical solution of flame spread rate was derived by formulating energy balance in each zone. When the calculated flame spread rates were compared with the measured ones, a quantitative agreement was recognized. This model would be applicable to other thermally thin high-thermal-conductivity materials as well as the CFRP sheets and therefore contribute to the fire risk assessment of such materials. (C) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.