Smoke is the main cause of death in tunnel fires. It is one of the important measures to maintain smoke stratification in the early stage of tunnel fire. This article focused on experimentally studying the combined effect of lateral concentrated smoke extraction and longitudinal ventilation on the smoke stratification, which never be revealed before. The velocity of the smoke layer and air layer, vertical temperature distribution, and the flow patterns of the smoke were measured. It was found that the longitudinal ventilation and lateral concentrated smoke extraction would affect the flow of the smoke and change the shear velocity between the smoke layer and air layer, then, the patterns of the smoke layer will be affected. And the flow patterns with Froude (Fr) number can be classified into three categories: (a)Fr < 0.6, with stable smoke stratification; (b) 0.6 < Fr < 0.85, with a stable smoke stratification but the blurring interface; and (c) Fr > 0.85, the smoke layer is completely unstable. The result can provide a reference for ventilation design of immersed tube tunnels.

中文翻译：

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横向集中排烟对纵向通风隧道烟气分层影响的实验研究

烟雾是造成隧道火灾的主要死亡原因。这是在隧道火灾初期保持烟气分层的重要措施之一。本文的重点是通过实验研究侧向集中排烟和纵向通风对烟雾分层的综合影响，这是以前从未发现过的。测量了烟层和空气层的速度，垂直温度分布以及烟的流型。研究发现，纵向通风和侧向集中排烟会影响烟气的流动，改变烟层与空气层之间的剪切速度，进而影响烟层的形态。Froude（Fr）数的流型可以分为三类：（a）Fr <0.6，烟气分层稳定；（b）0.6 <Fr <0.85，烟气分层稳定，但界面模糊；（c）Fr> 0.85时，烟层完全不稳定。研究结果可为沉管隧道通风设计提供参考。