Water Spray Dynamics in Fire Flows

Abstract

Lagrangian model of droplet movement in axisymmetrical fluid flow is considered in application to water sprays in active fire control systems, such as sprinklers, aerosols and water mists. In contrast to previously known models equations of droplet motion are integrated in much more general form, with axial flow velocity being arbitrary function of two spatial coordinates. Second major advantage of the model is that it fully accounts for the droplet evaporation. Explicit formulas are derived for vaporization rate density and drag force at any location in the flow. Such formulas are directly applicable in a number of fire engineering problems, for example in estimating compartment cooling rates by water sprays, and in studying smoke layer destabilization by sprinkler or water mist sprays.