CFD simulations of the Cutting extinguisher

Developing tactics for extinguishing fires located in civil structures is needed. Nowadays, the most commonly procedure employed by most fire brigades when extinguishing fires located in the interior of buildings, consists in sending a unit of firefighters inside the structure spraying water on the surface of the burning fuels. This procedure has enormous caveats since it leads to the unavoidable necessity of exposing personal to situations where risks to their personal safety are major. An alternative to these tactics consists on using the Cutting extinguisher which in principle allows combating a fire by injecting water mist into the burning building without the necessity of entering it. This work studies the capabilities and limitations of the Cutting extinguisher when used for fire-fighting activities in conventional and idealised civil structures by the aid of computerised simulations and experimental data. The simulations were done using Fire Dynamics Simulator (FDS) which is an open-source code for modelling well-ventilated fires while experimental data was obtained from idealised and controlled fires and experiments. Findings of this study suggest that the Cutting extinguisher is effective for combating fires of moderated size in confinements using less water than traditional methods by reducing the relative concentration of oxygen in the room instead of by cooling the fuels as traditional methods do. The high velocity of the jet induces mixing in the confinement, enhancing the interaction of droplets with hot combustion products and promoting the vaporisation of the injected water. Furthermore, the induced momentum to the gases in the room together with the vaporisation of the injected water reduces the overall gas temperature inside the structure