Wind-tunnel studies on the characteristics of indoor/outdoor airflow and pollutant exchange in a building cluster

Abstract

The diffusion of air pollutants in urban areas is essentially a multiscale problem, which has aroused increasing concerns. Wind-tunnel experiments were employed to explore the characteristics of indoor/outdoor airflow and pollutant exchange in a building cluster. Under two wind directions ( β ​= ​0°,45°), smoke visualization tests were firstly conducted to visualize the diffusion characteristics of air pollutants released from different pollution sources. Then the 3D hot-film anemometer and SF 6 quantitative detector were used to measure the turbulence parameters and pollutant distributions. The smoke visualization tests showed that under β ​= ​0°, the pollutants were mainly concentrated in the middle main street canyons (S-1 and S-2), spread downstream, and were gradually diluted. However, the influence area under β ​= ​45° was wider. The results confirmed that the indoor pollutant concentration along different floors was closely related to that around the outside target building. The window-opening mode had great influence on indoor pollutant concentration, but little influence on the other floors. Additionally, when the pollution source was located in the building leeward wake, regardless of the building height, it could reduce the indoor air quality of the leeward building. This study is helpful to understand the characteristics of flow and dispersion through different urban scales. The configurations of multiscale diffusion models. • Wind-tunnel tests are employed to study indoor/outdoor exchange in a building cluster. • Two wind directions and different window opening modes are considered. • The smoke visualization tests allow the visualization of pollutant diffusion. • Pollutants in the building wake can diffuse vertically to the top leeward rooms. • The characteristics of pollutant diffusion through different urban scales are understood.