Abstract The smoke and air flow through a horizontal opening was investigated using a model-scale room equipped with a horizontal opening on the ceiling. A smoke layer was created under the ceiling using a small gas burner. The pressure difference across the horizontal opening was changed by controlling the air supply to and exhaust from the space above the opening. Smoke and air flow patterns were either downward uni-directional flow of air, bi-directional flow of air and smoke or uni-directional flow of smoke upward. By changing the pressure difference across the opening, critical pressure differences to cause uni-directional flow were determined. It was found that the critical pressure was 0.98 of the smoke layer buoyancy for the onset of upward uni-directional smoke flow, and 0.47 for downward uni-directional air flow. From the measured carbon dioxide concentration, the mass flow rates of smoke and air were calculated and correlated with the non-dimensional pressure difference in the case of bi-directional flows.

中文翻译：

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在小压差下通过水平开口的质量流量

摘要 使用在天花板上配备有水平开口的模型房间，研究了通过水平开口的烟雾和空气流动。使用小型燃气燃烧器在天花板下产生烟雾层。通过控制开口上方空间的供气和排气来改变水平开口两侧的压差。烟气流动模式为向下单向气流、气烟双向流动或烟气向上单向流动。通过改变开口两侧的压差，确定了导致单向流动的临界压差。发现向上单向烟流开始时烟层浮力的临界压力为0.98，向下单向气流开始时为0.47。