Sin Chung Hyok, Cui Peng-Yi, Jon Kwang Song, Luo Yang, Shen Jiao-Wen, Huang Yuan-Dong
School of Environment and Architecture, University of Shanghai for Science and Technology, Yangpu District, No. 516, Jungong Road, Shanghai, China.
Natural Science Center, Democratic People's, Kim Il Sung University, Taesong District, Pyongyang, Democratic People's Republic of Korea.
Air Qual Atmos Health. 2023;16(4):817-839. doi: 10.1007/s11869-023-01314-3. Epub 2023 Feb 13.
With continuous global warming, growing urban population density, and increasing compactness of urban buildings, the "void deck" street canyon design has become increasingly popular in city planning, especially for urban streets located in tropical areas. Nevertheless, research on traffic pollutant dispersion in street canyons with void decks (VDs) is still at its early stage. This study quantitatively evaluates the effects of void deck height and location on the canyon ventilation and pollutant dispersion in asymmetric street canyons with void decks, and the pollutant exposure risk level for pedestrians and street dwellers. Void decks introduce more fresh air, thereby greatly improving the ventilation properties of the asymmetric canyon. The air exchange rate (: 147.9%, 270.9%) and net escape velocity (*: 416.7%, 915.8%) of the step-up and step-down canyons with VDs (3 m high at full scale) at both buildings are higher than those of regular asymmetric canyons. Moreover, the mean dimensionless pollutant concentration () on the building wall and pedestrian respiration plane in which VDs are located stands at a low level, because pollutants are removed by the airflow entering or exiting through the void decks. Increased VD height (4.5 m at full scale) enhances the strength of airflow flowing into and out of the canyon, significantly increasing (177.3%, 380.9%) and * (595.2%, 1268.4%) and decreasing the mean on both pedestrian respiration planes and canyon walls. In particular, the values on both pedestrian respiration planes and both walls are almost zero for the canyons with VDs at both buildings. Therefore, among the three VD locations, both VDs provide the best living environment for pedestrians and near-road residents. These findings can help to design urban street canyons for mitigating traffic pollution risk and improving ventilation in tropical cities.
随着全球持续变暖、城市人口密度不断增加以及城市建筑日益紧凑，“架空层”街道峡谷设计在城市规划中越来越受欢迎，特别是对于位于热带地区的城市街道。然而，关于带有架空层（VDs）的街道峡谷中交通污染物扩散的研究仍处于早期阶段。本研究定量评估了架空层高度和位置对带有架空层的不对称街道峡谷通风和污染物扩散的影响，以及行人和街道居民的污染物暴露风险水平。架空层引入了更多新鲜空气，从而大大改善了不对称峡谷的通风性能。带有架空层（全尺寸3米高）的阶梯式上升和阶梯式下降峡谷在两栋建筑处的空气交换率（：147.9%，270.9%）和净逃逸速度（：416.7%，915.8%）高于常规不对称峡谷。此外，位于架空层所在建筑墙壁和行人呼吸平面上的平均无量纲污染物浓度（）处于较低水平，因为污染物通过进入或流出架空层的气流被去除。增加架空层高度（全尺寸4.5米）增强了流入和流出峡谷的气流强度，显著增加了（177.3%，380.9%）和（595.2%，1268.4%），并降低了行人呼吸平面和峡谷壁上的平均。特别是，两栋建筑都带有架空层的峡谷在行人呼吸平面和两面墙壁上的 值几乎为零。因此，在三个架空层位置中，两个架空层为行人和路边居民提供了最佳居住环境。这些发现有助于设计城市街道峡谷，以降低热带城市的交通污染风险并改善通风。
