Simulation of Fire Extinguishing Agent Transport and Dispersion in Aircraft Engine Nacelle

The flow and dispersion characteristics of the fire extinguishing agent in the pipings and the concentration distribution in the nacelle are essential for optimizing the aircraft fire extinguishing system. In the present work, we developed a three-dimensional CFD model to simulate the transport and dispersion of the agent in piping and nacelle. The results show that the length and structure of the pipings near the nozzles affect the concentration, pressure, flow rate, and flow distribution of the extinguishing agent. The smaller the bend of the pipings near the nozzles and the angle of connection with the main piping, the less time it takes for the agent to reach the nozzles and the more mass flow rate of the agent is injected, which is more conducive to extinguishing fire rapidly. External ventilation and the blockage of the nacelle’s ribs and other components impact the concentration distribution of the fire extinguishing agent in the nacelle. The agent is mainly concentrated in the middle and rear areas of the engine nacelle. Agent concentration tests were carried out in the simulated engine nacelle. The experimental result is similar to the simulation result, which verifies the feasibility of the simulation method. The simulation method can be used to increase the concentration of fire extinguishing agent to meet the safety requirements by changing the outside ventilation and increasing the filling amount of fire extinguishing agent, so as to achieve the optimization of the fire extinguishing system.