客机货舱火灾时期污染物的非稳态扩散规律研究

Unsteady State Diffusion of Pollutants During Cargo Compartment Fire

针对火灾条件下客机货舱气体输运与烟雾扩散的问题,建立了基于体积火源的火灾分析模型,采用有限体积法求解了三维非定常N-S方程、组分输运方程,分析了货舱内温度场和污染气体以及烟尘的非稳态扩散规律,并同实验结果对比验证了方法的可靠性。研究表明,货舱底部发生火灾后,热气流受到热浮力驱动形成"天花板喷流"现象,污染物随高温气流向货舱顶部聚集并向背离火源的水平方向扩散,顶部污染物浓度达到饱和后逐步向货舱底部运动,形成了远离火源位置处污染物浓度随高度减小而减小的现象。研究为机舱火灾预警提供了参考依据。

The transport of the pollutant gas and smoke in aircraft cargo compartment is investigated numerically on the occurrence of fire disaster. The analysis model based on the volume fire source is established. The 3D unsteady Navier-Stokes equations and transport equations are solved using finite-volume method. The distribution of the temperature is achieved and the unsteady transport principle of pollutant gases and the smoke is analyzed. Numerical results match well with the experiments results, which verifies the correctness of the numerical method. Results show that the ceiling spray behavior is observed when the thermal air is driven by the buoyancy force once fire rises at the bottom of the cargo. The pollutants quickly gather towards the top of the compartment accompanying with the hot air and diffuse towards the horizontal direction away from the fire source. Pollutants move towards the bottom of the cargo after the concentrations reaches saturation near the top of the compartment, which results in the phenomenon that the concentrations of the pollutants declines with the decrease of the height away from the fire source. The study provides references for the installation of smoke alarms.