考虑通风效应的飞机货舱烟雾探测器布局

Layout of smoke detector for aircraft cargo compartment considering ventilation effect

目前较多机型的飞机货舱都带有通风功能,探究通风效应对飞机货舱烟雾扩散的影响并确定通风工况下货舱内的烟雾探测器布局对飞行安全具有重要意义。采用计算流体力学方法建立DC-10飞机货舱火灾烟雾扩散数值模型,仿真分析火灾烟雾的流场特征;采用流场本征正交分解(POD)理论揭示通风对火灾烟雾流场的影响机理;采用仿真与实验相结合的方法研究通风工况下货舱内的烟雾探测器布局,并通过实验对比3种不同探测器布局的响应性能。结果表明:通风会抑制火灾烟雾的向上扩散,并延缓烟雾到达货舱顶棚的时间;随着通风量的增加,流场中小尺度无序流动模态所占能量的比例增加而烟雾贴近货舱顶棚进行贴壁运动的大尺度流动模态能量占比减小,导致烟雾到达顶棚的时间延长;在通风的飞机货舱内,最佳的探测器布局是将探测器安装在靠近货舱角落远离通风口的位置。

The cargo compartments of most current aircraft types are equipped with ventilation function.It is of great significance for flight safety to explore the influence of ventilation effect on smoke diffusion in the cargo com-partment and determine the layout of smoke detectors in the cargo compartment under ventilation conditions.A numerical model of fire smoke in DC-10 aircraft cargo compartment is established by using computational fluid dynamics method,and the flow field characteristics of fire smoke are analyzed by simulation.POD flow field orthogonal decomposition theory is used to reveal the influence mechanism of ventilation on fire smoke flow field,the layout of smoke detector in smoke cargo compartment under ventilation condition is studied by simulation and experiment.The results show that ventilation can inhibit the upward diffusion of fire smoke and delay the time for smoke to reach the cargo compartment ceiling.With the increase of ventilation volume,the energy proportion of small and medium-sized disordered flow modes in flow field increased,while the energy proportion of large-scale flow modes of smoke moving close to the cargo ceiling decreased,which resulted in a longer time for smoke to reach the ceiling.By comparing the response performance of the three different detector layouts experimentally,it is concluded that the optimal detector layout is to install the detector near the corner of the cargo hold and away from the vent.