| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Shuhei Gifu University, Faculty of Engineering, Assistant Professor, 工学部, 講師 (40293542)
HANAMURA Katsunori Gifu University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (20172950)
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| Budget Amount *help |
¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 2001: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2000: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1999: ¥800,000 (Direct Cost: ¥800,000)
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| Research Abstract |
Flame spread over thin PMMA films was investigated under normal gravity and micro-gravity conditions. A scale analysis was preformed and the result states that the flame spread is driven by the heat conduction in gas phase when there is free convection. On the other hand, under quiescent condition or in the presence of mildly convective flow, the radiation loss becomes significant and it can affect flame spread rate. In the first year, we measured downward spread rates over thin PMMA films under normal gravity, and confirmed that the result of the scale analysis agrees with the experimental results. In the second year, drop experiments were carried out with varying opposed-flow velocity, and we found that the spread rate had minimal value when the relative flow velocity was small. It implies that radiation loss decreases the spread rate, which was predicted by the scale analysis. In the third year, we measured the temperature field near the flame. The results well supported the phenomena that were predicted by the scale analysis. When the opposed-flow velocity decreases, the scale of the preheat zone increases. In such situation, the ratio of radiative heat transfer to the conductive heat transfer increases. The radiation loss increases with the increase in fuel thickness, with the decrease in oxygen level, and with the decrease in the flow velocity relative to the flame. When the heat loss excesses over a certain value, the steady heat balance in the solid preheat zone breaks, then the extinction occurs.
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