Concurrent flame spread over electric wire insulation was studied experimentally in microgravity conditions during parabolic flights. Polyethylene insulated Nickel-Chrome wires and Copper wires were examined for external flow velocities ranging from 50 mm/s to 200 mm/s. The experimental results showed that steady state flame spread over wire insulation in microgravity could be achieved, even for concurrent flow. A theoretical analysis on the balance of heat supply from the flame to the unburned region, radiation heat loss from the surface to the ambient and required energy to sustain the flame propagation was carried out to explain the presence of steady spread over insulated wire under concurrent flow. Based on the theory, the change in heat input (defined by the balance between heat supply from flame and radiation heat loss) was drawn as a function of the flame spread rate. The curve intersected the linear line of the required energy to sustain the flame. This balance point evidences the existence of steady propagation in concurrent flow. Moreover, the estimated steady spread rate (1.2 mm/s) was consistent with the experimental result by considering the ratio of the actual flame length to the theoretical to be 0.5. Further experimental results showed that the concurrent flame spread rate increased with the external flow velocity. In addition, the steady spread rate was found to be faster for Copper wires than for Nickel-Chrome wires. The experimental results for upward spreading (concurrent spreading) in normal gravity were compared with the microgravity results. In normal gravity, the flame did not reach a steady state within the investigated parameter range. This is due to the fact that the fairly large flame spread rate prevented the aforementioned heat balance to be reached, which meant that such a spread rate could not be attained within the length of the tested sample.

在抛物线飞行过程中的微重力条件下，对并发火焰蔓延到电线绝缘层进行了实验研究。检查聚乙烯绝缘的镍铬线和铜线的外部流速范围为50 mm / s至200 mm / s。实验结果表明，即使在同时流动的情况下，也可以在微重力下实现稳态火焰在导线绝缘层上的扩散。对火焰到未燃烧区域的供热，从表面到周围环境的辐射热损失以及维持火焰传播所需的能量之间的平衡进行了理论分析，以解释在并发流动下绝缘电线上稳定扩散的情况。 。根据理论，根据火焰蔓延速率绘制热量输入的变化（由火焰提供的热量和辐射热损失之间的平衡定义）。该曲线与维持火焰所需能量的直线相交。这个平衡点证明了并发流中存在稳定传播。此外，通过将实际火焰长度与理论值之比视为0.5，估计的稳定扩散速率（1.2 mm / s）与实验结果一致。进一步的实验结果表明，同时火焰的蔓延率随着外部流速的增加而增加。另外，发现铜线的稳定扩展率比镍铬线快。将在正常重力下向上扩展（并行扩展）的实验结果与微重力结果进行了比较。在正常重力下，火焰在所研究的参数范围内未达到稳态。这是由于以下事实：相当大的火焰蔓延速率阻止了前述的热平衡，这意味着在测试样品的长度内不能达到这样的蔓延速率。