Dai Yuwei, Mak Cheuk Ming, Zhang Yong, Cui Dongjin, Hang Jian
Department of Building Services Engineering, The Hong Kong Polytechnic University, Hong Kong, PR China.
School of Atmospheric Sciences, Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies, Sun Yat-sen University, Guangzhou, 510275, PR China.
Build Environ. 2020 Mar 15;171:106673. doi: 10.1016/j.buildenv.2020.106673. Epub 2020 Jan 21.
Interunit dispersion problems have been studied previously mainly through on-site measurements, wind tunnel tests, and CFD simulations. In this study, a scaled outdoor experiment was conducted to examine the interunit dispersion characteristics in consecutive two-dimensional street canyons. Tracer gas ( ) was continuously released to simulate the pollutant dispersion routes between the rooms in street canyons. The wind velocity, wind direction, air temperature, and tracer gas concentrations were monitored simultaneously. Two important parameters, the air exchange rate and reentry ratio, were analyzed to reveal the ventilation performance and interunit dispersion of the rooms in the street canyons. Based on the real-time weather conditions, it was found that the ventilation performance of the source room varied according to the room location. The air exchange rate distribution of the leeward-side room was more stable than that of the windward side. The tracer gas was mainly transported in the vortex direction inside the street canyon, and the highest reentry ratio was observed at the room nearest to the source room along the transportation route. In addition, under real weather conditions, the rooms in the street canyon have a high probability of experiencing a high reentry ratio based on the maximum reentry ratio of each room. This study provides authentic airflow and pollutant dispersion information in the street canyons in an urban environment. The dataset of this experiment can be used to validate further numerical simulations.
单元间扩散问题此前主要通过现场测量、风洞试验和计算流体动力学（CFD）模拟进行研究。在本研究中，进行了一次缩尺户外实验，以研究连续二维街道峡谷中的单元间扩散特性。持续释放示踪气体（ ），以模拟街道峡谷中各房间之间的污染物扩散路径。同时监测风速、风向、气温和示踪气体浓度。分析了两个重要参数，即空气交换率和再进入率，以揭示街道峡谷中各房间的通风性能和单元间扩散情况。基于实时天气条件，发现源房间的通风性能因房间位置而异。背风侧房间的空气交换率分布比迎风侧更稳定。示踪气体主要在街道峡谷内部沿涡旋方向传输，并且在沿传输路线最靠近源房间的房间处观测到最高的再进入率。此外，在实际天气条件下，根据每个房间的最大再进入率，街道峡谷中的房间有很高的概率经历高再进入率。本研究提供了城市环境中街道峡谷内真实的气流和污染物扩散信息。该实验数据集可用于进一步验证数值模拟。
