城市街道内机动车排放污染物NO对流扩散的特征

采用现场观测和数值模拟的方法研究了城市街道内机动车排放污染物中的NO扩散特征。结果表明:城市街道中机动车排放污染物的对流扩散取决于屋顶风向和风速,随着建筑物顶部气流速度的增大,街道内同样位置的污染物浓度相对减小;当风向垂直于街道轴线时,街道内同样位置的污染物浓度最大;同时街道内机动车排放的污染物浓度与车流量成正比关系,即机动车流量越大污染物浓度越高。

An Experimental and Numerical Simulation Study on Vehicle Exhaust NO Dispersion in a Street Canyon

In order to study the properties of pollutant concentration induced by traffic in a street canyon,a method of both experimental investigation and numerical simulation was used.The results showed that pollutants related traffic in a street canyon were characterized by large temporal variability which was not only related to the diurnal variation in the traffic flux but also influenced by the meteorology condition.The street concentration level of traffic pollutant related was directly proportional to traffic flux and inversely proportional to wind speed at the roof of buildings,and with the air flow direction at the roof level perpendicular to the street,pollutant concentration on walls at leeward side was the highest.