Investigation of door width towards flame tilting behaviours and combustion species in compartment fire scenarios using large eddy simulation

Numerical assessment on a large-scale compartment buoyant fires was performed to investigate the effect of exit door width on the flame tilting behaviour, evolution of the thermal layer and formation of combustion species. The simulations were performed using an in-house large eddy simulation (LES) based fire field model incorporating subgrid-scale (SGS) turbulence, detailed chemical kinetics combustion, soot and radiation models. A comprehensive set of simulation case studies have been carried out with various doorway opening sizes, to investigate the influence of the incoming air entrainment towards the deflection angle of the flame. In addition, the changes in the thermal interface, neutral plane and major chemical species profiles (i.e. CO/CO₂) are also studied in detail. The fire model was validated against experimental measurements. It was found that increasing the door width elevates the neutral plane height and its correlated layer height of concentrated toxic gases. In addition, there is a critical door width (4/6) that produced the minimum fire tilting angle, deviation from the minimum door width results in an increase in flame tilting angle. It was discovered the centre fire have a range of titling angle between 58° to 75°, with a variation of 25% from 2/6 to 8/6 doorway sizes. This also totally affects the dynamics of the CO₂ profiles with the compartment room, in which the concentrated toxic gas layer ascends as the fire is more ventilated. In general, it was discovered that having a large doorway size is mainly contributing to reduce the potential fire hazards in a one-opening compartment room fire scenario. The relation of compartment fire tilting can be critical especially for the design of fire protection systems. © 2020 Elsevier Ltd.