辐射热流条件下多层电缆着火的数值模拟

通过CFD计算软件对锥形量热燃烧实验条件下的多层电缆着火性能进行数值模拟计算,对比相应CONE电缆燃烧实验结果,其计算结果表明所建立的电缆模型所得计算结果能够较好预测电缆着火时间。在此基础上,对护套层、绝缘层厚度、线芯层直径等参数对着火时间的影响进行了分析,发现护套层厚度对着火时间影响最大,线芯层对着火时间影响较小;当护套层及绝缘层厚度达到一定数值之后,电缆着火时间将不再发生变化。另外,因为电缆由多层热特性各异的材料组成,不能简单的划分为热薄材料或者热厚材料,但就所模拟电缆而言,其着火时间在不同的热辐射强度下分别表现出与热薄材料或者热厚材料相似的变化规律。

Numerical simulation of multilayer cable ignition under radiant heat flux

The surface temperature of cable under the cone calorimeter test has been simulated with CFD package. The predicted ignition time is acceptable comparing to the results of cone calorimeter experiments of the same cable. The influence of the thickness of coating layer, insulation layer and the diameter of conductor have been studied based the CFD model. The results indicate that the coating layer is the major influence factor while the diameter of conductor has minor effect. It is found that once the aggregate thickness of the coating layer and insulation layer is beyond certain values, the ignition time of the cable remains unchanged. In addition, since cable is made of several materials with different thermal properties, it cannot be simply classified as thermally-thick or thermally-thin material. However, the cables examined in this paper show similar the ignition times with thermally-thick materials or thermally-thin materials respectively under different radiant heat fluxes.