Heat transfer at interfaces of a container of high-energy materials immersed in a pool fire

Containers of high-energy materials accidentally exposed to sooting fires may undergo a thermally induced reaction that can cause losses to human life and catastrophic damage to the surroundings. The time to explosion depends on the amount of heat reaching the explosive. The thermal conditions at the fire/container and container/explosive interfaces introduce major uncertainties in the prediction of this time. The main goals of this work were: (a) to develop an understanding of the dominant modes of soot deposition onto containers in jet fuel pool fires; (b) to quantify the effects of these deposits on the heat flux to the container; (c) to identify controlling mechanisms of heat transfer at the steel/explosive interface, and (d) to provide computer models capable of describing the findings.; The fire/container interface was studied using a surrogate explosive container and a water-cooled calorimeter immersed in a jet fuel pool fire. The soot buildup was measured with a wet film gage with an uncertainty of 20%. The deposition model consisted of solving the boundary layer equations and the thermophoretic transport of soot particles along the cylinder surface. The model accurately predicted deposition rates and it was therefore concluded that thermophoresis was the dominant soot transport-mechanism controlling the deposition of soot on the container wall. Soot in the freestream and soot buildup were found to have an important insulating effect on the heat transfer into the container. A soot deposit thickness of 1.2 mm resulted in as much as a 35% reduction in heat flux.; Fast cookoff experiments were used to study the container/explosive interface. Duhamel superposition and inverse heat conduction equations were used to infer heat flux directly from measured internal temperatures. A thermal reaction model was developed for predicting the time to explosion and determining the relevant mechanisms of heat transfer. It was found that differential thermal expansion of the materials led to the formation of a gap at the steel/explosive interface and that this gap caused a significant thermal contact resistance that considerably increased the time to explosion.