What is the problem being addressed? Why is it important for society?
Aeronautical on-board fire suppression systems, e.g. the one found in the cargo compartment, are based on the interruption of the propagation of chain reactions typically found in aeronautical fuels. These fire suppression systems historically used hydrofluorocarbons (HFCs) as a fire protection fluid. Even small concentrations of these fluids in the air are sufficient to stop the reaction. The most common fire extinction agent has been Halon (R13B1, CFBr3), however due to their high global working potentials (GWPs), industry has been pushed towards more environmentally friendly alternatives. Several alternatives are being evaluated, in particular Novec-1230 Fire Protection Fluid. Novec-1230 is a sustainable HFCs alternative that works quickly, cleanly and efficiently. The main difference between Halon and Novec-1230 is, in addition to the lower global warming potential of the latest, its higher molecular weight. As a result, the boiling point at ambient pressure of the latter is much higher which results in a more difficult vaporization and dispersion. It is therefore necessary to redesign the complete fire suppression system and in particular, to develop new simulation and modelling tools to be able to predict, in advance, the behaviour and performance of the new fire extinction agents.
What are the overall objectives of FireExtinction?
1. Perform a critical assessment of existing models for phase change and their applicability to current fire suppression agents and feasibility of coupling with multiphase solvers.
2. Implement a selection of the state of the art models of phase change, specifically adjusted for rapidly depressurised multicomponent mixtures, as a user function of a two-phase/multi-phase simulation solver using a Eulerian-Lagrangian approach.
3. Carry out an experimental campaign with at least two different extinction agents and relevant conditions.
4. Perform a high-fidelity direct numerical simulation in a reduced domain where most of the physical scales are obtained. Validate some of the results using the experimental data available from the experiments of point 3.
5. Use the results of point 4: First, develop and calibrate an improved multi-drop model used in an Eulerian-Lagrangian approach and, second, develop a sub-grid two-phase model for a two phase Eulerian-Eulerian computational fluid dynamics (CFD) multiphase solver.
6. Conduct a parametrical study of realistic conditions (flight phases and operational conditions defined by the Topic Leader) of the fire suppresser using both, the Eulerian-Eulerian and Eulerian-Lagrangian CFD U-RANS models developed in point 5. Compare both approaches in terms of accuracy and efficiency.
7. Develop a useful simulation and predictive tool for multiphase discharges, to be exploited by the aeronautical industry in the definition and design of the new fire extinction systems.
