This paper presents a full-scale experimental research on the smoke descent and stratification in a two-storey residential building under the coupling influences of vertical connection channels and ventilation conditions. The two floors were connected by one atrium and one stair, and the fire source was located on the second floor. Wood crib and gasoline were selected as representative fuels to reflect typical residential fire scenarios, with heat release rates of 82 kW and 140 kW, respectively. The states of the building openings were varied to simulate different ventilation conditions. Results showed that the smoke tended to spread in the ridge direction due to the structural limitations of slope roofs. The temperature distribution in both the ridge and slope directions was obtained. A special “three-zone” smoke stratification structure including upper smoke layer, intermediate air layer and lower smoke layer is observed, which is significantly different from the well-known “two-zone” model. The “three-zone” stratification resulted in a nonmonotonic vertical temperature distribution in the atrium. The lower smoke layer thickness Zl,g was found to be greatly affected by ventilation conditions. Based on the boundary layer theories and the law of energy conservation, a series of expressions were established to calculate Zl,g and intermediate air layer thickness δw, which are the key parameters of the “three-zone” stratification. The theoretical calculations matched the experimental data well and explained the sharp trends of δw and Zl,g under different ventilation conditions. This study can provide theoretical guidance about fire detection, smoke exhaust and people evacuation in residential buildings.

中文翻译：

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不同通风条件下两层建筑烟雾下降和分层的全面实验研究


本文对垂直连接通道和通风条件耦合影响下的两层住宅建筑烟雾下降和分层进行了全面的实验研究。两层由一个中庭和一个楼梯连接，火源位于二楼。选择木婴儿床和汽油作为代表性燃料，以反映典型的住宅火灾情景，热释放率分别为 82 kW 和 140 kW。建筑物开口的状态是不同的，以模拟不同的通风条件。结果表明，由于坡屋顶的结构限制，烟雾倾向于沿屋脊方向蔓延。得到了山脊和坡向的温度分布。观察到一种特殊的“三区”烟雾分层结构，包括上烟层、中间空气层和下烟层，这与众所周知的“两区”模型明显不同。“三区”分层导致心房垂直温度分布非单调。发现较低的烟层厚度 Zl，g 受通风条件的影响很大。基于边界层理论和能量守恒定律，建立了一系列表达式来计算 Zl，g 和中间空气层厚度 δw，它们是“三区”分层的关键参数。理论计算与实验数据吻合较好，解释了不同通风条件下 δw 和 Zl，g 的急剧变化趋势。本研究可为住宅建筑的火灾探测、排烟和人员疏散提供理论指导。