Synthesis of firebrand knowledge and research
Spotting ignition by lofted firebrands is a significant mechanism of fire spread, as observed in many large scale fires. The phenomenon of spotting fires comprises three sequential mechanisms: generation, transport and ignition of a receptive fuel. In order to understand these mechanisms, many experiments have been performed, such as measuring drag on firebrands, analyzing the flow fields of flame and plume structures, collecting firebrands from burning materials, houses and wildfires, and observing firebrand burning characteristics in wind tunnels at terminal velocity and ignition characteristics of fuel beds. The knowledge obtained from the experiments has been used to develop firebrand models. Since Tarifa developed a firebrand model based on the terminal velocity approximation, many firebrand transport models have been developed to predict maximum spot fire distance. Combustion models of a firebrand have been developed empirically and the maximum spot fire distance has been derived. Recommendations for future research and development include the mechanisms of firebrand formation and generation rates, improved combustion and flow field models for firebrand transport, and energy production and transfer associated with firebrand ignition of fuel beds.
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