摘要
该文用数值模拟方法对城市街道峡谷内的机动车排放活性污染物扩散进行了研究,并分析了机动车排放中的NOx与大气中的臭氧在太阳辐射的环境下发生的光化学反应对街道峡谷内污染物传输、扩散以及分布产生的影响。研究发现,街道峡谷中的流场导致NOx在背风面产生累积,在给定的条件下,近地面处NOx浓度达到7.5×10-6左右,且随高度的增高而减小,污染物随着气流从背风面上升,流向街道峡谷中线再扩散到迎风面,其浓度也呈逐渐降低趋势;同时由于光化学反应的进行,在背风面一侧附近臭氧的浓度偏低。并对T 10oC和T 4oC两种温差下的污染物分布进行了比较,结果显示:增强地面受热能够加快气流的运动,T 10oC的情况下,背风面附近的NOx浓度较低,而迎风面一侧的NOx浓度较高。这一结果表明增强地面受热能够促进背风面积聚的污染气体向街道峡谷上方和迎风面一侧运输和扩散。
In this paper, the characteristics of reactive vehicle emission dispersion in urban street canyon are investigated by using CFD technique, and the effects of the photochemical reactions between NOx and ozone are examined in the presence of bottom heating. The CFD results show that NOx accumulates in the leeward side that NOx concentration reaches 7.5 ppm near the ground, but ozone accumulates in the windward side as the result of chemical reactions. Stronger heating intensity accelerates the air flow and makes more pollutant move to the top of the canyon and near the windward wall. Pollutants concentration with different heating intensity of △T= 10℃ and △T=4℃ is compared. With the heating intensity of △T= 10℃, there is a lower NOx concentration near the leeward wall and a higher NOx concentration near the windward wall.
出处
《水动力学研究与进展（A辑）》
CSCD
北大核心
2013年第2期159-166,共8页
Chinese Journal of Hydrodynamics
基金
国家自然科学基金(50808124)~~
关键词
街道峡谷
光化学反应
臭氧
street canyon
photochemical reaction
ozone
