【摘要】 采用经风洞实验验证的数值模型（标准k-ε模型）研究了树冠尺寸与建筑高度改变对街谷内自然通风及污染物扩散的影响。考虑了3种树冠尺寸与4种街谷结构，并采用无量纲浓度K与空气交换率ACH分别对街道峡谷内污染程度与通风性能进行评估。结果表明，建筑高度与树冠尺寸改变会显著影响街谷内气流流动结构。上游建筑高度增加与树冠尺寸增大不利于街谷内的环境通风与特定区域的污染物扩散。树冠尺寸的减小会增强街道峡谷的通风性能，从而改善街道峡谷内的空气质量，但在一些特定结构的街道峡谷内，树冠尺寸的改变对ACH的影响并不明显。更多还原

【Abstract】 The effects of canopy size and building height on natural ventilation and pollutant diffusion in street canyons were studied using the numerical model(standard k-ε model)validated by wind tunnel experiments. Three canopy sizes and four street-canyon structures were considered, and the dimensionless concentration(K) and air exchange rate(ACH) were adopted to evaluate the pollution degree and ventilation performance of the street canyons. The results show that the change of building height and canopy size can significantly affect the air flow structure and environmental ventilation in street canyons. Here, the increase of the upstream building height and canopy size is not conducive to the environmental ventilation and the diffusion of pollutants in specific areas of the street canyons. The reduction of canopy size can enhance the ventilation performance of street canyons and improve the air quality therein. However, in some street canyons with specific configurations, the effect of canopy size change on ACH is not obvious.更多还原