Experimental and numerical study of fire behaviour: effects of the width on the rate of spread
| Autor: | Anthony Collin, Nicolas Trevisan, Alexis Marchand, Pascal Boulet |
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| Přispěvatelé: | Laboratoire Énergies et Mécanique Théorique et Appliquée (LEMTA ), Université de Lorraine (UL)-Centre National de la Recherche Scientifique (CNRS), Viegas, Domingos Xavier (ed.) |
| Rok vydání: | 2014 |
| Předmět: |
Materials science
Meteorology Cellular automaton model Autoignition temperature Mechanics Heat transfer coefficient Fire propagation Twig law.invention Ignition system [SPI]Engineering Sciences [physics] Physics::Plasma Physics law Cone calorimeter Emissivity Radiative transfer Fire front width effect Physics::Chemical Physics Residence time (statistics) |
| Zdroj: | VII International Conference on Forest Fire Research VII International Conference on Forest Fire Research, Nov 2014, Coimbra, Portugal. ⟨10.14195/978-989-26-0884-6_18⟩ |
| Popis: | International audience; In this work, the effect of the diameter on the ignition of twigs of Cistus Monspeliensis was studied experimentally and theoretically. For this, piloted ignition experiments were carried out in a cone calorimeter. In the first part of the study, the location of ignition, the ignition time and the flame residence time were investigated according to the twig diameter. Different modes of ignition were observed. The ignition could be due to: glowing of embers; flaming near the solid; spark of the pilot. The ignition time and the flame residence time increase strongly with the diameter. For small diameters, ignition time can be considered as proportional to the diameter. For high diameters, the ignition time tends to stabilize around a constant value (about 80 s). The second part of the study was devoted to the modelling of the temperature evolution in a twig. A one-dimensional nonhomogeneous heat-conduction problem was considered in finite medium. An optimization was performed to determine the model parameters (ignition temperature, twig emissivity and total heat transfer coefficient). From the expression of temperature in the twig, the ignition time was calculated for the various diameters. The comparison between these values and the experimental data shows a good agreement. Finally, a sensitivity analysis was carried out highlighting the influence of the ignition temperature and of the total heat transfer coefficient on the results. |
| Databáze: | OpenAIRE |
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