微小重力環境における低速空気流中の ポリエチレン被覆導線の燃焼挙動

抄録

Opposed flame spreading over polyethylene insulated wire in low air flow velocity has been investigated under microgravity environment. The experiments were performed at Japan Microgravity Center ( JAMIC) 10 s dropshaft. Four samples of different insulation thickness, 0.075, 0.15, 0.3 and 0.5 mm, with the same inner core diameter, 0.5 mm, were used. Experiments were performed with changing O2 concentration, 21-50％, and external air flow velocity, 0 (quiescent)－20 cm/s. The results show that flame shape changes strongly depending on air ｆｌow velocity and oxygen concentration. The flame spread rate is affected by air flow velocity, and the effect is much stronger in high oxygen concentration. According to the results, flame spread phenomenon of wire insulation is classified into four different regimes based on air flow velocity, namely, (1) oxygen supply control regime, (2) geometrical effect regime, (3) thermal regime and (4) chemical kinetic control regime. In low ‰ow velocity region such as ventilation air in spacecraft, maximum flame spread rate appears in between the regime (1) and (2). The regime (2) is the one special for the wire insulation, firstly pointed out in the present paper, where the flame spread rate increases with decrease in external ‰ow velocity under strong wire geometrical effect, i.e. wire thickness and surface curvature.