FDS Simulation of the Combined Use of Sprinklers and Water Mist Fire Extinguishing Systems

The purpose of this study is to investigate the effect of sprinkler water droplets with relatively large diameter on the movement of several orders of magnitude smaller water mist particles. The aim of the simulation is to analyze the flow field under a 1m x 1m shelf element with installation height of 1.5 m in the middle of the room, with and without n-heptane tray fire, using combined sprinklers and water mist extinguishing systems.

A CFD model, Fire Dynamic Simulator (FDS) version 5.5.3 was used for the numerical simulation. The data obtained from the numerical studies are analyzed.

As a result of the simulation, we have come to the following conclusions: water mist droplets of smaller diameter are forced to flow in the direction of the shelf environment by the sprinkler open-jet. Under the shelf, the velocities are higher than 1 m/s and vigorous turbulence can be observed. Water droplets of the mist can effectively reach a possible fire under tray. The results show that in the combined system, the sprinkler and water mist droplets can enhance each other’s effects.