The Gas Interface Formation and Diffusion Characteristics Analysis in Ship Equipment Design

在中庭等大型密闭空间发生火灾时，需要保证人员的安全疏散，因此烟雾管理系统的完美设计就显得尤为重要。在空气对流中热量和气体分布不平衡的情况下，天花板下自然会形成烟雾层，这可能会使烟雾散射现象变得复杂。为了有效地控制烟雾，本研究对中庭空间在火力作用下烟雾界面的形成和扩散特性进行了研究。应用剖面法推导了烟层界面的形成条件，并进行了实验验证。烟雾扩散分析考虑了动量、热量和烟雾传递方程中包含浮力效应的各向异性湍流吹风，并对烟雾的某些特性做了一些基本假设。对三层大中庭的数值计算结果表明，在中庭顶部驱动排烟扇可以有效地防止烟雾扩散。结果总结如下：(1)可以看出，目前的分析方法一般可以用来预测封闭空间内烟雾的扩散特性。(2)烟雾倾向于积聚在最高的甲板空间。(3)操作安装在顶棚上的排风机，排烟效果非常好。

In the event of spontaneous outbreak of fire in a large enclosed space such as an atrium, it is necessary that the personnel can be safely evacuated, whereby, the faultless design of the smoke management system becomes important. The natural tendency to form smoke layrs below the ceiling in the absence of properly balanced heat and gas distribution in the air convection, could make the phenomenon of smoke scattering complicated.This study makes an investigation of smoke interface formation and diffusion characteristics in an atrium-like space under fire for the purpose of effective smoke control. The formation condition of smoke layr interface is deduced by applying the profile method to the state equations, which was also confirmed experimentally. The analysis of smoke diffusino takes into account of an anisotropic turbulent blow with the buoyancy effects included in the momentum, heat and smoke transfer equations with a few basic assumptions made on some smoke properties. From the results of the numerical calculation in a three decked large atrium, it was clarified that by driving a smoke exhaust fan at the top of the atrium could effectively prevent the smoke diffusion.The results are summarized as follows.(1) It can be seen that the present analytecal method in general can be used to predict smoke diffusion characteristics in enclosed spaces.(2) Smoke tendds to accumulate the highest decked space.(3) It is very effective for purging smoke to operate the exhaust fan installed at top ceilling.