Wildfire spread experiments: Fluctuations in thermal measurements

This paper presents a set of four fire spread experiments conducted in the open (i.e. far from the laboratory scale). Plot areas range from 60 to 1250 m2. Thermal measurements, namely gas temperature and radiant flux densities, have been performed during the spread of large scale fire fronts. The data collected during these experiments are processed and discussed in order to evaluate the contribution to the thermal radiation of both long term and fluctuating parts of the temperature field. This study presents pioneering measurements about the heat transfer governing a wildfire spread in the open. Second, this work attempts to evaluate the incidence of fluctuations in thermal data. Using simple statistical assumptions we show that neglecting fluctuations of the thermal source can lead to underestimate the radiant flux density emitted ahead of the fire front and therefore, the related fire hazard.