Simtec Simulation of Flame Extinguishing by Ultra Fine Water Mist

In this simulation, Simtec was used to study effect of ultra fine water mist on flame. This is a comprehensive simulation, with turbulent flow, particle tracing, water mist evaporation, gas phase thermal radiation, particle thermal radiation and turbulent combustion, etc, all computed. In order to efficiently and reasonably well capture the water mist extinguish effect on flame, while without considering all the detailed chemical kinetics which will make the simulation extremely time consuming and extremely hard to use in practical engineering, a particular turbulent combustion model is developed in Simtec. 

A series of simulations were made, with variation of water mist concentration level. The simulation shows a critical water mist concentration of about 0.3 g/L. The flame will survive when the mist concentration is below this value and extinguish when the mist concentration is above this value. This is in a reasonable good agreement with experiment measurement which gives a critical mist concentration of about 0.375 g/L.

                        a) 3D view, 0.2 g/L                                                                                    b) Temperature slice view, 0.2 g/L

Flame can survive when subject to water mist concentration of 0.2g/L