Relative effects of inertia and buoyancy on smoke propagation in confined and forced ventilated enclosure fire scenarios

In this study, we focus on smoke propagation in confined and forced ventilated enclosure fire scenarios as it is a source of possible hazardous situations. The objective of the present contribution is to investigate the effect of the three physical mechanisms (buoyancy, gas expansion and forced ventilation) on diverse examples of smoke flow through transfer elements. Three types of pool fire scenario have been considered with several transfer elements typical of nuclear industry. The first scenario is a fire in one ventilated compartment and the propagation means are the release of smoke through the ventilation ducts. The second scenario is a fire in one ventilated room connected by a doorway to another ventilated room. The smoke flow investigated is the flow at the doorway. The last scenario is a fire in a ventilated compartment connected to an adjacent room with leakages. The smoke flow considered is a smoke leakage. Each scenario and the smoke propagation are analysed on the basis of large scale representative fire tests performed during the PRISME project and numerical simulations with a zone-modelling code, SYLVIA of IRSN. The results show ventilation is the driving mechanism for smoke propagation in the one-room configuration whereas buoyancy plays the major role for the doorway flow. Finally, depending on the kind of leakages, mechanical ventilation can act on the buoyancy-induced smoke propagation.

► Smoke propagation in confined and forced ventilated enclosure fire scenarios.
► We investigate the effect of the three physical mechanisms on diverse smoke flows.
► We show ventilation is the driving mechanism in the 1-room configuration.
► Buoyancy plays the major role for the doorway flow.
► Coupling buoyancy-ventilation for the leakage flow.