Heat sources and gaseous contaminants widely exist in modern buildings. Buoyancy-driven exchange flow through a large opening, such as a window, a doorway or an atrium, is ubiquitous in our daily life. Analogous experiments were carried out in a water tank to investigate the effect of vent location on the characteristics of the exchange flow. The model tank filled with coloured brine solution was immersed in a large reservoir filled with fresh water. The transient distribution of the reduced gravity is measured using a light attenuation technique. For the exchange flow through a vertical opening, the reduced gravity in the chamber is vertically stratified instead of uniformly distributed. Moreover, the density distribution was influenced by the location of the opening. The buoyancy-driven flow through a horizontal opening is highly oscillatory and the resulting density distribution is relatively uniform. Different models were proposed to estimate the ventilation flow rate through a vertical opening or a horizontal one. Hopefully, this study could provide useful advice with regards to the ventilation design and contaminant removal in buildings.

现代建筑中广泛存在热源和气态污染物。浮力驱动的交流流通过大开口（例如窗户，门道或中庭）在我们的日常生活中无处不在。在水箱中进行了类似的实验，以研究排气孔位置对交换流量特性的影响。将装有有色盐水溶液的模型罐浸入装有淡水的大型水箱中。使用光衰减技术测量重力的瞬态分布。对于通过垂直开口的交换流，腔室内减小的重力是垂直分层的，而不是均匀分布的。此外，密度分布受开口位置的影响。通过水平开口的浮力驱动的流动是高度振荡的，并且所得的密度分布相对均匀。提出了不同的模型来估计通过垂直开口或水平开口的通风流量。希望这项研究可以为建筑物的通风设计和污染物去除提供有用的建议。