Simulation on transport characteristics of fire extinguishing agent in aircraft fire extinguishing piping

This manuscript proposes a simulation model for studying aircraft fire suppression systems. The flow characteristics of the aircraft fire extinguishing system Halon 1301 are numerically simulated based on the simulation model. The experiments found that the agent discharge is divided into three phases, the first phase is the liquid holding discharge phase, the second phase is the two-phase discharge phase and the third phase is the nitrogen discharge phase. The beginning of the nitrogen discharge phase means that Halon 1301 is emptied from the bottle. By comparing the pressure change inside the bottle under different discharge pressures with the simulation calculation results, it is shown that the simulation model proposed in this manuscript can maintain a good simulation accuracy until the agent is emptied. The simulation model proposed in this manuscript was used to simulate a fire extinguishing system of an actual type of aircraft with a emptying time of 0.71s and a emptying pressure of 1.05MPa. The peak pressure, mass flow rate and flow rate at the nozzles were 0.138MPa, 7.28Kg/s and 108.48m/s respectively. The discharge mass ratio of each nozzle was 3.390:1.653:0.477:0.221.