下折弯电缆燃烧火蔓延行为试验研究  

Experimental study on the fire spread behavior of downward-bending cables

作　　者：陈长坤[1] 杜武豪 徐童 石朗 CHEN Changkun;DU Wuhao;XU Tong;SHI Lang(Institute of Disaster Prevention Science and Safety Technology,Central South University,Changsha 410075,China)

机构地区：[1]中南大学防灾科学与安全技术研究所,长沙410075

出　　处：《清华大学学报(自然科学版)》2025年第4期805-812,共8页Journal of Tsinghua University(Science and Technology)

基　　金：国家自然科学基金重大项目(72091512)。

摘　　要：电力电缆在长距离输电过程中常出现高差变化的情况,导致电缆出现折弯。为探究多根紧密并排敷设电缆中部(折弯段)被引燃条件下,电缆折弯角度及其数量对下折弯电缆火蔓延行为的影响,该文以三铝芯交联聚乙烯绝缘电缆为试验对象,开展电缆燃烧试验,测量并分析火焰温度、电缆火蔓延时间、平均火蔓延速率等关键燃烧特征参数。结果表明:电缆根数越多,火焰峰值温度与平均火蔓延速率越大;电缆平均火蔓延速率随折弯角度增加而增大,5根90°下折弯电缆平均火蔓延速率约为5.4 cm/min,约为水平电缆火蔓延速率的1.9倍。这主要是由于电缆折弯角度越大,电缆“火焰附壁”效应与高温熔滴的流淌作用更加显著,增强了电缆未燃区域所受的热对流和热辐射作用,进而导致电缆平均火蔓延速率增加。[Objective]Due to the height differences during the power transmission process,the bending installation of cables is a common method.The stress in the bending section of cables is usually relatively concentrated and more susceptible to damage,leading to a greater fire hazard.According to the different bending forms,the bending cables can be divided into upward-bending cables and downward-bending cables.[Methods]An experimental study was conducted to investigate the effect of the bending angle and number of cables on the flame spread behavior of downward-bending cables.[Results]Results show that:(1)the peak temperature on the cable surface of downward-bending cables gradually increases,as the number of cables increases.The temperature peak of 5 downward-bending with 60°bending angle was about 782.3℃,which was 1.8 times higher than that of a single cable at the same angle.This is mainly due to the fact that combustion of multiple cables laid side by side produces more combustible pyrolysis gases,while the flame has a stronger preheating effect on the cables.(2)As the bending angle increases the flame spread time of downward-bending cables is shortened and the average flame spread rate increases.Under the ignition condition of five 90°downward-bending cables,the average flame spread rate of the cables was 5.4 cm/min,which was 1.9 times of that of five 0°downward-bending cables;under the ignition condition of five 90°downward-bending cables,the temperature peak reached 868.3℃,which was about 1.4 times of that of that of five 0°downward-bending cables.This is mainly due to the larger bending angle,which was mainly due to the difference in the role of the flow of melt drippings on the cable under different bending angles,when the flame spread in the inclined section of the cables,the flow of high-temperature melt drippings was an important driving force to ignite the cables in the unburned section.As the bending angle increased,the force of gravity increased in the direction of the cables,and the drippings wer

关 键 词：电缆火灾 下折弯电缆 折弯角度 火蔓延 

分 类 号：X934[环境科学与工程—安全科学]