Abstract A series of experiments of the upward flame spread over polyethylene-coated wire with copper core were conducted in a newly designed high-pressure chamber to study the effects of the wire inclination angles and ambient pressures. The angle of inclination changed from 0° to 75° and the pressure ranged from 100 kPa to 400 kPa. The results show that the flame spread rate increases with the inclination angle and the pressure. The characteristic lengths including the flame length, the flame base width and the pyrolysis length present an increasing trend with increasing inclination angles, while the elevated pressure results in that the flame length and flame base width decreases and the pyrolysis length increases. Moreover, a simplified heat transfer analysis model considering the convective, radiant and conductive heat feedback is proposed to discuss the flame spread mechanism. Based on the theoretical analysis, convective heat transfer from flame and conductive heat transfer from wire core play significant roles in heating the unburned insulation with the increase of inclination angles. For the cases with higher pressure, the heat transfer from flame including heat convection and heat conduction plays a dominant role in increasing the heat feedback to the unburned wire.

中文翻译：

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高气压对火焰在不同倾角的电线上蔓延的影响

摘要 在新设计的高压室中进行了一系列向上火焰蔓延在铜芯聚乙烯包覆电线上的实验，研究了电线倾斜角度和环境压力的影响。倾角从0°变为75°，压力范围从100 kPa到400 kPa。结果表明，火焰蔓延速率随着倾角和压力的增加而增加。火焰长度、火焰底部宽度和热解长度等特征长度随着倾角的增加呈增加趋势，而压力升高导致火焰长度和火焰底部宽度减小，热解长度增加。此外，考虑对流的简化传热分析模型，提出辐射和传导热反馈来讨论火焰蔓延机制。理论分析表明，随着倾斜角的增加，火焰对流传热和线芯传导传热对未烧尽的绝缘体的加热起着重要作用。对于压力较高的情况，包括热对流和热传导在内的火焰传热在增加未燃烧导线的热反馈中起主导作用。