Abstract: In order to investigate the influence of high altitude environment on the dynamics of extinguishing agent flow and transport in aircraft cargo hold fire extinguishing system, this paper adopts Fluent software to numerically model and simulate the dynamics of extinguishing agent flow and transport in the pipeline network of a small Halon 1301 airborne fire extinguishing system device, and obtains the dynamics of transport and release in the pipeline network of Halon 1301 at altitude of 10 000 m and 13 000 m. The transport and release dynamics of Halon 1301 extinguishing agent in the pipe network at high altitude were calculated, and compared and analyzed with three characteristic variables, namely, pressure, phase volume fraction and phase change mass transfer rate during the transport and release process of extinguishing agent at the altitude of sea level. The results show that the transportation and release of extinguishing agents at high altitude follow the “three-phase” process, but the high altitude environment is not favorable to the flow and transportation of extinguishing agents. The results of this study can provide a theoretical basis for optimizing the flow and transport capacity of airborne fire extinguishing systems in high-altitude environments.

Key words: fluid simulation; aviation firefighting; airborne fire suppression systems; gas-liquid phase change; computational fluid dynamics