The laboratory polyethylene wire with different core diameters of 3 mm, 5 mm, 6 mm, 7 mm, 8 mm, 10 mm and 12 mm was used to study the flame spread characteristics. The flame spread could be divided into initial oscillation stage, stable oscillation stage and burn-out stage. With the increase of the copper core diameter, the flame width and flame area increased firstly and then decreased. For wires with intermediate copper core diameters of 6 mm, 7 mm, 8 mm and 10 mm, the relationship between flame area and core diameter was established as $A~d_c$, the total mass loss rate k with the copper core diameter d_c followed as $k\text{~}{d}_c$, and the combustion mass loss rate and dripping mass loss rate gradually equaled to each other at stable oscillation stage. By analyzing the temperature field during the process of flame spread, the temperature gradient was almost same for diameters from 3 mm to 10 mm, which demonstrated the radiation heat would be influenced by flame height. Combined with the increased flame spread, the dominant conduction heat transfer mechanism was built. When the diameter was 12 mm, the smaller conduction heat transfer, which illustrated the core material Cu played an cool effect on flame, thus the dominant heat transfer of Cu was changed from a heat source to a heat sink.

使用具有 3 mm、5 mm、6 mm、7 mm、8 mm、10 mm 和 12 mm 不同芯径的实验室聚乙烯线来研究火焰蔓延特性。火焰蔓延可分为初始振荡阶段、稳定振荡阶段和燃尽阶段。随着铜芯直径的增加，火焰宽度和火焰面积先增大后减小。对于中间铜芯直径为 6 mm、7 mm、8 mm 和 10 mm 的导线，火焰面积与芯径之间的关系为$\mathrm{一种}~d_C$，与铜芯直径d的总质量损失率k _Ç随后如$克\text{~}{d}_C$，且在稳定振荡阶段燃烧失重率和滴流失重率逐渐趋于相等。通过对火焰蔓延过程中的温度场进行分析，直径3～10mm的温度梯度几乎相同，说明火焰高度会影响辐射热。结合增加的火焰蔓延，建立了主导的传导传热机制。当直径为 12 mm 时，传导传热较小，说明芯材 Cu 对火焰起到了冷却作用，因此 Cu 的主要传热从热源转变为散热片。