A study for model of flame spread over solid fuel

In this study, the model for flame spread over solid fuel is investigated. To re-examine the analytical solution by de Ris, our experimental data on flame temperature and flame spread rate are used, which were obtained by the measurements of downward flame spread over filter paper sheets in uniform ambient atmosphere diluted with either N2 or CO2. In the analytical models, the assumption has been usually adopted that the reaction rate is infinite and steady state is achieved. Then, in our previous experiments, oxygen concentration was reduced at elevated temperature up to 150°C to confirm the limitation of analytical solution. Results show that, when the oxygen concentration is relatively high, the agreement of flame spread rates of analytical solution and experimental data is observed. However, decrease of the oxygen concentration reduces the flame temperature, and makes the flame spread unstable at some points. In this case, the analytical model can not predict the flame spread. This is explained by the fact that the assumptions for infinite reaction rate and steady solution are invalid.