Estimation of Heat Feedback from Fires Subsisting Multiple Fire Sources in Three Dimensions

Abstract

To understand the fire characteristics of multiple fire sources in three dimensions, we conducted a series of experiments using two small pool fires. As a result, mass burning rates for both pool fires are larger than that of a single pool fire, especially the mass burning rate for the upper pan remarkably increases compared with that for the lower pan. In this paper, the effects of external radiation and buoyant flow on mass burning rate were analytically examined. The external radiative heat flux was calculated using a cylindrical flame model. Additional convective heat flux due to induced buoyant flow by other fire source was estimated by modified Grashof number. The calculation results comparatively consist with experimental results. The calculation model was applied to examine the scale effect of fire sources for the upper pan. Additional convective heat transfer rate is larger than that of external radiation in small scale fire sources less than 0.2 m of diameter, while the external radiation becomes to be dominant heat transfer mode in fire sources above 0.5 m of diameter.