Abstract：
With continuous global warming, growing urban population density, and increasing compactness of urban buildings, VD (void deck) street design has become increasingly popular in city planning, especially in tropical countries. However, understanding on traffic pollutant dispersion inside the street canyons with VDs is still at early stage. This paper evaluates quantitatively the effects of VD location and wind direction on the ventilation and traffic pollutant exposure inside the street canyon with VDs. The results show that under seven wind directions (0°, 15°, 30°, 45°, 60°, 75°, and 90°), the VD provides higher ACH than that of the regular canyon, especially at high α (angle between the approaching wind and the canyon axis). Also, mean K (dimensionless pollutant concentration) values of the canyon wall and pedestrian respiration plane on one side where VD is located are significantly reduced compared to the regular canyon. Therefore, when VDs are at both buildings, both pedestrian respiration planes and walls have the lowest K values, thus providing the best living environment for pedestrians and near-road residents. In addition, as α increases, the K values on both respiration planes significantly decrease except for the leeward respiration plane of the canyon with the windward VD. These findings can help to design urban street canyons for mitigating traffic pollution risk and improving ventilation in tropical cities with frequently changing wind directions.
摘要：
随着全球持续变暖,不断增长的城市人口密度，增加城市建筑的紧凑性，VD（虚空甲板）街道设计在城市规划中越来越受欢迎，尤其是在热带国家。然而,对带有VD的街道峡谷内交通污染物扩散的了解仍处于早期阶段。本文用VD定量评估了VD位置和风向对街道峡谷内通风和交通污染物暴露的影响。结果表明，在七个风向(0°，15°,30°,45°,60°,75°,和90°)，VD提供比常规峡谷更高的ACH，特别是在高α（接近的风和峡谷轴之间的角度）。此外，与常规峡谷相比，VD所在一侧的峡谷壁和行人呼吸平面的平均K（无量纲污染物浓度）值显着降低。因此,当视频在两栋大楼时，行人呼吸平面和墙壁的K值最低，从而为行人和近路居民提供最佳的生活环境。此外,随着α的增加,除峡谷的背风呼吸平面为迎风VD外，两个呼吸平面上的K值均显着降低。这些发现可以帮助设计城市街道峡谷，以减轻交通污染风险，并改善风向经常变化的热带城市的通风。
