高层居民住宅污染物垂直跨户传播机理研究

Investigations on the airborne infection cases in high-rise residential(HRR) buildings found that the exhausted airflow from the window in single-sided natural ventilation could go into the immediate upper floor through its window opening and subsequently cause cross-infections. So far the research on the vertical transport of pollutants is very limited. Based on the theory of buidling ventilation and fluid dynamics, the two main vertical transport routes of pollutants in typical chinese plate-type HRR buidlings will be studied, i.e."indoor space→exterior space→indoor space" and "indoor space→internal vertical channel→indoor space". Through field measurements, wind tunnel experiments and large eddy simulations, we will clarify the influences of two-way airflows at the window, internal stack effect and vortex flows around the building driven by the wind on the movement of gaseous pollutants and particulate matters in the windward, leeward and side of the building. Secondly, the transient characteristics, such as transport speed and concentration fluctuation features in the flow field around a building with and without thermal effect will be investigated. Finally this study focuses on the combined effect of wind and buoyancy pressure under different Richardson numbers and the infection risk distributions in various flats based on the Wells-Riley model. The purpose is to reveal the vertical transport mechanism of pollutants under different meteorological conditions. The results are definitely helpful for the design of natural ventilation in HRR buildings.

高层居民住宅传染病传播案例的研究发现单侧自然通风时下层窗户的排风会通过上一楼层的窗户进入该层室内，造成各楼层之间的交叉感染。目前针对此类污染物垂直传播现象的研究还十分有限。本项目从建筑通风和流体力学基本理论入手，针对"户内→建筑外部空间→户内"和"户内→建筑内部垂直通道→户内"两种主要传播路径，以典型的板式高层住宅为例，采用实地测量、风洞模型实验和大涡模拟相结合的技术路线，首先分析热压作用下外墙通风窗的双向流动、建筑内部的烟囱效应和风压作用下建筑外围的涡旋流场对气态和颗粒态污染物在迎风侧、背风侧和垂直风向侧竖向传播的影响；其次考虑非稳态特性，明确传播速度和建筑物绕流与自然对流时的浓度脉动特征；最终考察不同理查森数下热压与风压共同作用的结果，并结合Wells-Riley公式研究不同楼层感染概率的差异。研究结果有望揭示不同气象条件下污染物垂直跨户传播的机理，为高层民宅自然通风设计提供理论依据。