On the theory of flashover development

The role of thermal radiation on the initiation of flashover in a compartment fire

“…Physically, the radiant feedback to a fuel surface has been recognized as an important mechanism leading to the onset of flashover [13][14][15][16][17]. Indeed, without the presence of a radiation source such as the compartment wall or soot particulates within the hot gas, a gas layer temperature of 600 C might not be insufficient to generate the required floor heat flux of 20 kW/m 2 required for flashover.…”

“…While the zone model cannot predict localized spatial behavior of field variables such as temperature, mass concentration of various species and velocity, the model is generally expected to be sufficiently good in illustrating the key mechanisms leading to flashover, provided that all relevant physical processes are simulated with sufficient accuracy. Another advantage of the zone model is that it can be readily adapted to a nonlinear analysis using computational techniques of non-linear dynamics [16][17][18][19], which can be a powerful approach both in identifying and understanding the key mechanisms leading to flashover.…”

Deterministic–stochastic approach to compartment fire modelling

“…However, even a qualitative description of the phenomenon is not easy to obtain, both because of the complexity of the physical model, which must take into account the radiative heat exchange between the flame, the fuel and the surroundings, and because most of the physical and environmental parameters (such as the burning surface and the ventilation conditions) are variable in time in a way that is generally not predictable a priori. Flashover and extinction jumps ( Thomas et al 1980;Bishop et al 1993a,b;Graham et al 1995), as well as the hysteresis between the fuel-controlled and ventilation-controlled regimes have been experimentally observed and recast in mathematical models. More recent studies have aimed at understanding other parametric effects, such as the effect of the thermal inertia of the walls (Graham et al 1999), of the discharge coefficient (Beard 2001) and of the aspect ratio of the compartment (Beard 2003).…”

“…More recent studies have aimed at understanding other parametric effects, such as the effect of the thermal inertia of the walls (Graham et al 1999), of the discharge coefficient (Beard 2001) and of the aspect ratio of the compartment (Beard 2003). In particular, mathematical models with one Graham et al 1995Graham et al , 1999, two (Bishop et al 1993a,b) or three state variables (Beard et al 1994-95;Beard 2001Beard , 2003 are available in the literature.…”

On Zone Models For Flashover

“…dimensionless parameters in (5) heat release rate of fire parameter in the Table incident heat flux to the fuel bed from the fire parameters in the Table temperature time total time for fire growth from ignition to flashover effective convective heat transfer coefficient in [I] dimensionless parameter in (6) emissivity of upper layer and of smoke parameters in the Flashover phenomena (the transition from a small growing fire to a fully developed fire) often accompany the development of compartmented fires. It is well understood that these phenomena are realised because of enhancement of the burning rate by factors, such as radiation from a hot smoke layer, saturation of the compartment environment by oxygen from the external atmosphere through an opening, etc.…”