CFD Predictions of Fire Spread over Wood Cribs in Large Open-Plan Compartments under Two Different Ventilation Conditions

Fire spread behaviours occurring under different ventilation conditions in a large-scale compartment are explored by means of a CFD-based numerical simulator coupled with a multi-component pyrolysis model. The model captures differences in the burning behaviours between the scenarios, showing the role of pre-heating in supporting enhanced burning rates. In the less well-ventilated test this gives rise to a sharp increase in fire spread rates, which are eventually more than doubled, representing a transition to a growing fire, and ultimately a fully-developed fire. The analysis also discriminates the role in stick ignition between the evolving fluxes from the flame in the fire plume and externally (i.e. those from hot layer and compartment boundaries), showing that flame fluxes become progressively less important, more rapidly, in the less well-ventilated test. These results highlight the value of comprehensive modelling approaches which exploit detailed solid-phase pyrolysis models, capturing the fire evolution in different ventilation conditions, thereby permitting exploration of the fire spread behaviours in manners which are inaccessible experimentally