可燃性固体の燃え拡がりに及ぼす周囲雰囲気の影響 : 第2報,希釈の影響と気相の温度測定(熱工学,内燃機関,動力など)

概要

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To investigate effects of ambient atmosphere on flame spread, an experimental study has been conducted. The downward flame spread over solid fuel has been examined in a combustion chamber with a vertical duct to obtain uniform ambient atmosphere. The flame spread rate is measured with constant inflow velocity. Two kinds of paper sheet are used as samples. Ambient temperature is increased up to 150℃, and oxygen concentration is reduced to examine the diluent effect, adding carbon dioxide and nitrogen to the ambient air. The gas temperature is measured by thermocouples. Results show that, the flame spread rate is decreased with a smaller oxygen concentration, resulting in smaller heat flow into the preheat region, Q. Diluent effect of carbon dioxide is larger than that of nitrogen to reduce flame spread rate, with larger limiting oxygen concentration. In the gas temperature distribution, the maximum temperature is located around the flame zone, which is defined as the flame temperature. As oxygen concentration is decreased, the flame temperature is reduced. Hence, as the flame temperature is decreased, the heat flow into the preheat region is resultantly smaller. The temperature where the flame can not propagate is almost constant for all cases. Therefore, at extinction limit, the flame temperature is low so that the flame spread can not be supported due to smaller Q.
一般社団法人日本機械学会の論文
2003-04-25