弱浮力下导线绝缘层着火先期特性的研究

本文在低压弱浮力环境中模拟了微重力过载电流时导线绝缘层的着火先期过程,研究了压力对绝缘层着火先期特性的影响。结果表明,2 A时,绝缘层的温升率和最终平衡温度随压力降低而不断增大,模拟出了微重力下绝缘层的温升特性;10 A时,随着压力降低,绝缘层存在三种破坏机制;在不同区域压力对着火延迟时间的影响不同。最后,提高环境氧气浓度修正了低压对化学反应速率的抑制。结果表明,当压力在一定范围内降低时,随着氧气浓度的提高,绝缘层的着火极限范围拓宽,着火延迟时间缩短,可以初步模拟微重力下绝缘层的着火先期过程。

Study on Pre-Fire Characteristics of Wire Insulation by Overload in Weakly Buoyant Environment

Experiments were conducted to study the effect of pressure on the pre-fire characteristics of wire insulation in a low pressure setup.Results show that under 2A the temperature change rate and balanced temperature of wire insulation increased with the pressure decreasing,which could predict the pre-ignition temperature variations in microgravity.Under 10 A,there are three kinds of undermining mechanisms of wire insulation in different pressure.And the pressure has varied influences on the ignition delay time in different ranges.Finally,the oxygen concentration is increased to enhance the chemical reaction rate prohibited greatly in the low pressure.Results show that the range of flammable limit is broadened and ignition delay time is shortened with the increasing of oxygen concentration.Thus the method could be applied to predict the pre-fire process of wire insulation in microgravity to some extent.