Modeling the interaction between a spray of water droplets and turbulent combustion: application for fire extinction process by water mist

In the context of fire safety and to fight against the development of a fire in a confined building, a major objective is to improve the processes of extinction and one which is widely known: spray of water mist. Numerical simulations should be able to predict the efficiency of water mist by evaluating precisely the spatial-temporal evolution of fire characteristics in the vicinity of water droplets sprayed on. In order to determine liquid or vapor mass fraction of water, the combustion products concentration as well as temperature levels everywhere in the local, we introduce here the development of a model able to describe reactive gas where the flame stability is more or less affected by the water mist. An Eulerian-Eulerian two-phase flow formalism is used to describe water droplets which interact with the reactive gas by cooling and diluting it with water vapor coming from evaporation process. The underlying combustion model is the multi-fraction mixing approach with species determination diagram involving a competitive flammable and non-flammable domain. The final models have been implemented in Code-Saturne, a computational fluid dynamics software recently modified for fire studies. The validation of these models is performed from experimental of literature, and full scale cases. (author)