Abstract: In order to study the diffusion characteristics of automotive emission NOx under the condition of highway pavement thermal radiation，the CFD simulation models of automobile emission NOx dispersion in real atmospheric environment were built． The numerical simulation of three-dimensional unsteady turbulent flow was achieved，combining with the test of meteorological parameters and measured concentration of single vehicle; the diffusion characteristics of NOx were obtained． The results show that with the increase of pavement temperature，transportation effect on automobile emission is enhanced． At 10m vertical distance to the exhaust port along the direction of the automobile exhaust，at the height of Person’respiratory level，the NOx concentration still has a higher value． The numerical results are compared with the measured concentration and a good agreement is achieved，as well as the reliability of the CFD model is validated．

Key words: environmental engineering, pollutant diffusion, highway pavement thermal radiation, numerical simulation

摘要： 针对公路沥青路面热辐射，建立了三维大气流动及机动车排放物扩散的CFD 仿真模型，进行了非定常三维湍流流动模拟; 结合气象因素及单车排放NOx扩散浓度的实地测试，研究了路面热辐射对机动车排放物扩散的影响。结果表明: 路表加热作用所产生的热力环流使得污染物能够被有效地输送和扩散至上空，从而使得近地面的污染物浓度下降; 随地表温度增高，输送效应增强; 在尾气排放方向处于距排气口10 m 远处，人的呼吸带高度处NOx浓度仍然较高; NOx扩散浓度的模拟值与实测值具有较好的符合，验证了数值模型的可靠性。

关键词: 环境工程, 尾气扩散, 路面热辐射, 数值模拟