Convective heat transfer in fire spread through fine fuel beds

摘要: An extensive set of wind-tunnel fires was burned to investigate convective heat transfer ahead a steadily progressing fire front moving across porous fuel bed. The effects and environmental variables on the gas temperature profile ‘surface wind speed’ (gas velocity at bed surface) are reported. In non-zero winds, air near surface decays exponentially with distance from front. zero decreases rapidly within very short flame front, then slowly thereafter. maximum as free stream speed, packing ratio moisture content increase. characteristic exponential decay increases strongly speed area-to-volume fuel. depends lesser extent ratio, depth content. There three general regimes for flow: (1) constant flow approximately half flow, far front; (2) an intermediate zone minimum characterised by low or reversed flow; (3) region where rises almost velocity. boundaries between regions move further increasing in way which is only slightly affected geometry.