中文摘要：

耦合微观交通仿真和机动车尾气排放模型,分别对含信号控制人行横道和不含信号控制人行横道的街道峡谷污染物排放进行计算,并以此为排放源,采用k-ε两方程模型与组分输运方程对风向与街道垂直时的污染扩散情况进行了三维数值模拟.结果表明,k-ε两方程模型与组分输运方程可以较好地模拟风向与街道垂直时三维街道峡谷内的污染物扩散情况.峡谷两端边缘均产生一个水平漩涡,而峡谷中部产生垂直的顺时针漩涡,越靠近峡谷中部,漩涡与地面的夹角越接近90°.受信号控制人行横道影响,峡谷中部迎风面和背风面的污染物浓度比不含信号控制人行横道模拟结果明显偏高,分别是其污染物浓度的2.5倍和2.7倍.在靠近背风面一侧污染物浓度达到18.88mg.m-3,超出国家二级标准88.84%.

英文摘要：

Pollutant emissions in the street canyon with and without signals for pedestrians crossing were calculated by coupling traffic micro-simulation software with a vehicle emission model.With the simulation result as the emission source input,the flow and concentration field of the three-dimensional street canyon with the wind direction perpendicular to the street were modeled based on a k-ε model and the species transport equation.The result showed that the k-ε model and species transport equation can describe the pollutant dispersion in the three-dimensional street canyon well when the wind direction was perpendicular to the street.Two significant flow patterns can be discovered,corner eddies at the ends of the street canyon and a canyon vortex in the middle part of street canyon.The closer to the middle of street canyon,the angle between canyon vortex and the ground was nearer to 90°.The pollutant concentrations of windward and leeward side in the middle of the street canyon with signals for pedestrians crossing were 2.5 times and 2.7 times higher than the canyon without signals for pedestrians crossing.The pollutant concentration of the windward side was 18.88 mg.m-3,which was 0.89 times higher than the second National Standard.