中文摘要：

利用k-ε湍流模型对怠速条件下汽车排气污染物在排气尾流中的扩散特性进行了研究．汽车尾流中CO2浓度变化规律的模拟计算结果与实测数据具有很好的一致性．数值分析了排气浓度、速度、方向以及侧风强度等对怠速条件下汽车污染物在排气尾流中扩散的影响．研究结果表明，排气出口污染物浓度的变化将改变排气尾流中污染物浓度的大小，但尾流扩散区域的结构基本保持不变；排气速度会直接影响到污染物在尾流下游的穿透距离及显著向上扩散的位置；相对排气浓度和排气速度而言，排气方向对尾流结构及污染物在尾流中的扩散与分布具有更大的影响；侧风对排气尾流的结构同样具有重要的影响，它可以有效地改变汽车排气尾流的扩散方向和污染物的浓度分布．

英文摘要：

The k-ε eddy dissipation model was used for the numerical simulation of the dispersing characteristics of vehicular exhaust plume under idle condition, The simulated results match very well with the experimental results, The effects of the initial emission concentration, exit velocity, exit direction and crosswind intensity were investigated parametrically. The initial pollutant concentration can increase the local concentrations but the pattern of dispersion remains the same. The exit velocity can increase the momentum of the jet, resulting in a deeper penetration downstream. The exit angle has stronger influence on pollutant dispersion than both initial pollutant concentration and exit velocity. Crosswind shows a significant effect on the dispersion of the exhaust plume also. It can divert the plume to disperse in the same direction of the wind with limited penetration in the downstream direction.