Computational modeling of the condensed phase aerosol based fire extinguisher

The computational modeling of a novel condensed phase aerosol based fire extinguisher is considered in this study to assess its operational details and performance. A solid propellant is present inside the canister which is ignited using piezoelectric actuators producing hot fire extinguishing gases. The cooling of these hot gases is facilitated by a matrix of chemically active cooling pellets placed along the canister which condenses hot gas and discharges solid aerosol particulates. The initial experimental investigation of the extinguisher carried out at the premises of an industrial partner showed that improper cooling of the hot gases by pellets can lead to high temperature of the effluent gases and sparks at the exit. A decision was made to use modeling to develop better understanding of the physics of the extinguisher performance and develop improved experimental procedure using computational fluid dynamics model. A one dimensional computation has been established initially in the study by solving Euler's equations using the Finite Volume Method. Based on the results obtained, high fidelity three-dimensional computation of the problem, by solving the multi-component combustion gas flow inside the extinguisher, using Navier Strokes equations has been done. While detailed chemical kinetics are not accounted for in the process, initial experimental estimates of these processes are used in the simulations to account for the effects on dynamics of the process. The computed results show how improper cooling by the pellet region may lead to hot spots in the extinguisher. These results will be used in the improved experimental design.