Simulation Study on Aircraft Fire Extinguishing Pipeline with Different Filling Conditions and Pipeline Characteristics

Abstract

The filling conditions and pipeline characteristics of the aircraft fire extinguishing system determine the pressure of the fire extinguishing cylinder outlet, the discharge quality of the extinguishing agent, and the flow distribution during the discharge process. The simulation model of the fire extinguishing system pipeline of an aircraft was established by Amesim. The influence of filling conditions and pipeline characteristics was studied. It was found that the mass curves of the fire extinguishing agent were similar under filling pressures of 4, 5, and 6 MPa with a filling amount of 5.55 kg. The lower the initial temperature is, the pressure at the outlet of the cylinder decreases, but the emptying time is similar to 1.22 s. The lower the roughness is, the faster the discharge is. Under the ideal smooth pipe (ε = 0 mm), the emptying time of the fire extinguishing cylinder is 0.72 s. When the diameter of the short branch pipe is 10 mm, and the diameter of the long branch pipe is 14 mm, the discharge quality of the two pipes is close. The larger the diameter of the main pipe, the higher the discharge rate. The research results have a certain guiding significance for the pipeline design of certain aircraft.