城市小区环境流场及污染物扩散的风洞实验研究

介绍了一次有关城市小区环境流场和污染物扩散规律的风洞实验研究．实验以位于北京市东南部的方庄小区为研究对象，以1：250的缩尺比在南京大学MU环境风洞中建立模型并进行实验．实验包括：小区气流分布测量、小区空气污染物浓度分布测量、建筑物周边气流分布测量、建筑物周边空气污染物浓度分布测量．实验结果表明：小区内水平流场分布受不同高度建筑物影响，但风速垂直分布总体上仍符合幂指数律．小区内污染物分布亦受到建筑物及环境风速大小的影响．单体建筑物流场试验结果清晰显示了气流遇建筑物后的抬升翻越过程，以及街渠内的抽风效应，该效应可使街渠内风速达到来流的2～3倍．单体建筑物污染物分布试验结果显示随着离源的距离增大污染物浓度逐渐减小，其垂直分布仍符合地面源排放的扩散分布形式，实验结果与实际观测结果相比较为接近．相应数值模拟结果与风洞实验结果进行比较表明：两的气流和污染物浓度分布除个别有差异外，总体上相当吻合．

Experimental Study in Wind Tunnel in the Field of Air Flows and Pollutant Dispersion in the Urban Sub-domain

An experimental study in wind tunnel on rules of the distribution of streamlines and dispersion of pollutants in the urban sub_domain is described in the paper. In this experiment we set up a model with the ratio 1 to 250 for Fangzhuang residential area in the southeast of Beijing in wind tunnel. This experiment measured air flows and air pollution concentrations in the urban sub_domain as well as air flows and air pollution concentrations around buildings. The results indicate that horizontal field of air flows is affected by buildings that are of various heights in the urban sub_domain. However, the distribution of vertical wind speed is in accordance with power law. The distribution of air pollution concentration in the urban sub_domain is also affected by buildings and wind speed. The results on streamlines around a single building indicate that air flows lift in front of the building and then get across it, and effects of ventilation can raise wind speed 2 or 3 times faster. Around a single building pollution concentrations will decrease as the distance from measuring point to source increases. Vertical distribution of pollution concentrations is in accordance with the rules of source on the ground. The experiment is well compatible with observations. Comparisons between numerical model and wind tunnel experiment indicate that numerical model results on air dreams and pollution concentrations tally with wind tunnel experiment as a whole, except several differences in detail.