摘要:
为研究城市空间结构对汽车尾气扩散规律,根据高分辨率遥感影像建立了某城市核心区域几何模型。以当地常年气象风向作为重要的边界条件之一,应用CFD多相流技术,模拟了十字交叉口车辆队列怠速等候35,45,55 s时的尾气扩散过程,并对45 s时4个监测点的体积分数进行了实测,最后,通过建筑高度优化,降低了该区域的尾气含量。以上研究结果表明:在空间狭小区域,近地空间CO体积分数达1.0×10-7,与研究域平均体积分数相差100倍以上,说明城市空间结构对尾气扩散影响较大,仿真所揭示的规律与实测吻合。建筑设计时应结合当地气象风向和风速,应设计一定的建筑高度梯度,可以促使污浊气体迅速扩散至远地空间。
Abstract:
For study the influence law of the urban space structure on the automobile exhaust diffusion，the paper established an urban core region geometry model from high resolution remote sensing image． Based on the important boundary conditions meteorological wind，using CFD and multiphase flow，the diffusion processing of the vehicle queue exhaust at a crossroads during idle waiting of 35s，45s、55s were simulated，and the volume fractions of four monitoring stations at 45 seconds were measured． At last，building heights were optimized and the automobile exhaust contents reduced． Some conclusions were as follows: in narrow space，CO volume fraction near-earth space was up to 1. 0 × 10 － 7， and more than 100 times of the entire study area average value． Urban space structure had great influence on automobile exhaust diffusion． The laws deduced from simulation agree with the measurement． Local meteorological wind direction and speed should be considered and some height gradient should be selected in buildings structural layout，promoting the exhaust spread rapidly to the urban remote space．
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