The correlation between wind and convective heat transfer in a propagating fire

Background Wind speed is one of the major parameters that affect fire rate of spread and heat transfer in propagating bushfires. Aims Laboratory-scale experiments and physics-based simulations are used to derive a correlation between wind speed and convective heating and cooling of surface fuels in bushfire scenarios. Methods A low-speed wind tunnel was designed and built to conduct fire spread experiments using Excelsior fuel on a level test bed, with a packing ratio 0.03 and a moisture content of 10%. The wind speed was varied between 0 and 3.3 m s−1. Heat flux gauges and the retroreflective shadowgraph (RS) technique were used simultaneously to measure and visualise convective heat transfer. Simulations were conducted using the Fire Dynamics Simulator (FDS) to replicate the experimental study, enabling a detailed exploration of heat transfer modelling within the FDS framework. Key results The relationship between convective heat transfer and factors such as wind speed, flame angle, flame length and distance from the flame front was analysed and derived. Implications The results of this analysis reveal the mechanism of local convective heat transfer to downstream vegetation.