Fire Safety Science Digital Archive

Water sprays are being currently used for fire suppression in the essentially two distinctive regimes: as relatively coarse sprinkler sprays, or as fine water mists. The most efficient way of fire suppression is associated with the latter mode. For an efficient delivery and heat absorption the parameters of the spray, in particular droplet size must be optimized. In the present study, a criterion for the optimum spray dynamics is proposed, and an analytical estimation is provided for optimum droplet size in the spray as a function of Heat Release Rate of fire. Mathematical model is based on approximate solution of the Lagrangian equation for the motion of water droplets. The present approach provides a quick estimation of optimum spray parameters for a particular fire application. It is argued that a proper scientific definition of water mist sprays need be based on consideration of spray dynamics under specific fire conditions.