Cong BH, Liao GX (2004) 'Numerical simulation on fire suppression modeling by water sprays.' (Science Press Beijing: Beijing) 1257-1265

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Keywords:

fire suppression modeling,water sprays,gaseous suppression,surface,suppression,sprinkler interaction,mist suppression,diffusion flame,pool fires,extinguishment,extension,tunnel,plume,cfd,

Abstract: The present paper discusses fundamental aspects of mathematical modeling of fire suppression by water-based spray systems. Despite the fact that these systems have been used for a very long time, currently there are still no sufficiently accurate computational models to evaluate their performance and therefore facilitate their, intelligent design. The existing approaches to simulation of spray dynamics are discussed. In many cases, the most convenient and natural way is application of the Lagrangian tracking procedure. This method works reasonably well for coarse sprinkler sprays, but may face difficulties when applied to fine mist droplets. The criteria for application of the alternative, Eulerian-Eulerian two-phase model, and its features in comparison with the Lagrangian formulation are discussed. With regard to extinction modeling, surface and gaseous suppression are distinguished, and their relative importance in different situations is discussed. The gaseous extinction represents a great challenge in the case of buoyant turbulent flame with complex chemical kinetics. The successful suppression demands an optimum relation between the droplet size and the spray's integral momentum. The main task of surface suppression is to predict critical water flow rate required to suppress pyrolysis reaction of the combustible material. An analytical one-dimensional burning rate model of solid phase is employed for the surface extinction. As an illusion, examples of plastic pyrolysis suppression computation are considered. Predicted results include the gas temperature field, the surface temperature, and the heat flux distribution. Some relevant macroscopic combustion characteristics such as heat release rate, carbon dioxide and carbon monoxide yield rate, average surface temperature are also predicted and made a comparison with the measured data in the end.