Comparison of Limiting Oxygen Concentration between Concurrent-Flow and Opposed-Flow Flame Spreads over a Thin Paper Sheet in Microgravity

Int. J. Microgravity Sci. Appl. 2016p330109
Graduate School of Science and Technology, Hirosaki University
In order to compare the limiting oxygen concentration, below which a flame cannot continue to spread stably over solid materials, between concurrent-flow flame and opposed-flow flame spreads in microgravity, we have conducted parabolic flight experiments on flame spreading over a thin paper sheet (thickness: 0.12 mm and width: 20 mm) by varying the ambient air flow velocity. The two suction wind tunnels were mounted on the same aircraft and the opposed-flow and concurrent flow flame spread experiments were performed simultaneously. The air flows were driven by the pressure difference between inside and outside of the aircraft cabin, and the cross-sectional mean flow rate was obtained up to 7 cm/s. The oxygen concentration in the wind tunnel was controlled by adding nitrogen gas to the air flow sucked from the aircraft cabin. As a result, within the velocity range of the ambient flow from 1 cm/s to 7 cm/s, both limiting oxygen concentrations decreases as the ambient airflow rate increases. Moreover, it is found that although the propagation rate of the concurrent-flow flame spread is higher than that of the opposed flow flame spread at near limiting oxygen condition, both limiting oxygen concentrations of the concurrent-flow and opposed-flow flame spreads show almost the same values at the same ambient flow velocity.
Flame spread, Microgravity, Opposed flow, Concurrent flow, Limiting oxygen concentration

Received 24 August 2015, accepted 13 January 2016, published 31January 2016

© The Japan Society of Microgravity Applicaiton

この投稿文は次の言語で読めます: Japanese