Abstract
We studied numerically the flame spreading phenomena in a narrow circular duct made by PMMA in order to capture the time-depended transport processes during the event. The main aim of this study is to clarify the stability mechanism near the extinction limit (i.e. low Damkohler number limit) which is one of unique feature in this system, which might be different from the conventional flat-plate flame spreading as suggested in our previous works. Numerical model includes time-dependent mass and heat transfer with one-step finite rate of chemical reactions both in gas and solid phase. In this study, it is successfully simulated the nearly steady flame movement under the condition studied. Moreover, it is accomplished to reproduce the two distinctive spreading modes, such as the one belongs in thermal regime and chemical regime, which have already been observed experimentally. Although there is quantitative disagreement between experimental and numerical results, it is confirmed that our numerical model should be satisfactory to capture the qualitative behavior of flame spreading in the narrow duct.
