CFD investigation on flowing and discharging characteristics of airborne Halon 1301 fire-extinguishing agent at varied altitudes

To investigate the functioning mechanism of cruise altitude on transportation and discharging dynamics of onboard fire-extinguishants, a numerical model coupling the vaporization and flowing process is established for the Halon 1301-N₂ multi-component two-phase flow inside the onboard fire-extinguishing system based on computational fluid dynamics. Flowing and transportation parameters are simulated and compared for Halon 1301 at 0 m, 3000 m, 6000 m and 12000 m. Moreover, the peak discharging fluid pressure, velocity and density are also analyzed to evaluate the impact of altitude on discharging dynamics of Halon 1301. Notably, the maximum discharging velocity at 3000 m, 6000 m and 12000 m are reduced by 4 %, 9 % and 15 % relative to that at 0 m; the maximum discharging fluid pressure and density at 12000 m are respectively reduced by 32 % and 12 % relative to those at 0 m. High altitude is unraveled to inhibit the vaporization of Halon 1301 and lower the discharging efficiency at the pipeline outlet, consequently lowering the diffusion efficiency and effective concentration of Halon 1301 in the protected area and further weakening the fire-suppression effectiveness. The unveiled insights afford guidance for the optimization of fire-extinguishing systems to improve the fire-fighting capability of airplanes at high altitudes.