Influence of shrub hedge on CO diffusion in elevated bridge street canyons
-
摘要:
为探究灌木篱墙布局对高架桥街道峡谷内部流场及污染物扩散的影响，将灌木篱墙假设为多孔介质，采用标准k-$ \varepsilon $模型结合组分运输方程对布置中央灌木篱墙和两侧灌木篱墙的高架桥街谷的底部和桥面道路机动车排放的CO扩散过程进行模拟，并与风洞试验结果比较。结果表明：数值模拟方法可靠，且与标准街谷不同，高架街谷中的灌木篱墙不仅不会阻碍流场运动，还能加强底部受阻风场与上部风场的对流，有利于底部道路排放污染物的扩散，能够有效降低街谷的整体污染物浓度，改善污染物在背风侧、桥体上方和底部集聚的问题。两侧均设置篱墙时风场的上下对流更强，背风面壁面处CO质量分数降低60%，增设灌木篱墙可作为改善其内部空气污染程度的有效措施。
Abstract:To investigate the influence of shrub hedge layout on the flow field and pollutant dispersion in elevated bridge street canyons, the shrub hedges were assumed to be porous media, and the standard k-ε model was used in combination with the species transport equation in the simulation. The diffusion process of CO emitted from motor vehicles on the bottom and bridge deck of the elevated bridge street canyons with central two-side shrub hedges was simulated separately. The simulation results were compared and validated with wind tunnel test ones. The results indicate that this numerical simulation method is reliable, and unlike standard street canyons, the shrub hedges in elevated bridge street canyons not only do not hinder the movement of the flow field, but also enhance the convection between the blocked wind field at the bottom and top. This is beneficial for the dispersion of pollutants emitted from the bottom of the road, and can effectively reduce the overall pollutant concentration in the street canyon and improve the issues of pollutant accumulation on the leeward side, above the bridge deck, and at the bottom. When hedges are set on both sides, the convection between the upper and lower wind fields is stronger, and the CO concentration at the leeward wall is reduced by 60%. Therefore, adding shrub hedges can be an effective measure to reduce the level of air pollution in elevated bridge street canyons.
-
Key words:
- elevated bridge /
- shrub hedge /
- street canyon /
- pollutant diffusion /
- numerical simulation
-
图 3 数值模拟与风洞试验CO无量纲浓度对比
Figure 3. Comparison of dimensionless concentrations between numerical simulation and wind tunnel experiment for CO
图 4 不同布局的街谷内部风速云图
Figure 4. Wind speed contour maps inside street canyons with different layouts
图 5 不同布局的街谷内部流线
Figure 5. Streamline maps inside street canyons with different layouts
图 6 不同布局的街谷内部CO质量分数分布云图
Figure 6. Cloud maps of CO mass fraction distribution inside street canyons with different layouts
图 7 不同布局和污染源位置的街谷内部CO质量分数分布云图
Figure 7. Cloud maps of CO mass fraction distribution inside street canyons with different layouts and pollution source locations
图 8 背风侧建筑物壁面处CO质量分数垂直分布
Figure 8. Vertical distribution of CO mass fraction at leeward building facades
-
[1] PU Y C, YANG C. Estimating urban roadside emissions with an atmospheric dispersion model based on in-field measurements[J]. Environmental Pollution,2014,192:300-307. doi: 10.1016/j.envpol.2014.05.019 [2] BUCCOLIERI R, JEANJEAN A P R, GATTO E, et al. The impact of trees on street ventilation, NO x and PM2.5 concentrations across heights in Marylebone Rd street canyon, central London[J]. Sustainable Cities and Society,2018,41:227-241. doi: 10.1016/j.scs.2018.05.030 [3] 杨儒浦, 冯相昭, 王敏, 等. 城市交通部门温室气体和大气污染物协同减排潜力分析: 以唐山市为例[J]. 环境工程技术学报,2023,13(6):2033-2042. doi: 10.12153/j.issn.1674-991X.20230055YANG R P, FENG X Z, WANG M, et al. Analysis of synergic reduction of greenhouse gases and air pollutants emission in the urban transportation sector: taking Tangshan City as an example[J]. Journal of Environmental Engineering Technology,2023,13(6):2033-2042. doi: 10.12153/j.issn.1674-991X.20230055 [4] N'RIAIN C M, FISHER B, MARTIN C J, et al. Flow field and pollution dispersion in a central London street[J]. Environmental Monitoring and Assessment,1998,52(1):299-314. [5] GROMKE C. A vegetation modeling concept for building and environmental aerodynamics wind tunnel tests and its application in pollutant dispersion studies[J]. Environmental Pollution,2011,159(8/9):2094-2099. [6] LU K F, HE H D, WANG H W, et al. Characterizing temporal and vertical distribution patterns of traffic-emitted pollutants near an elevated expressway in urban residential areas[J]. Building and Environment,2020,172:106678. doi: 10.1016/j.buildenv.2020.106678 [7] 张永林, 吴睿, 杨孝文, 等. 典型城市道路交通加密监测点大气污染特征及影响因素[J]. 环境工程技术学报,2023,13(3):929-939. doi: 10.12153/j.issn.1674-991X.20221266ZHANG Y L, WU R, YANG X W, et al. Research on air pollution characteristics and influencing factors of typical urban road traffic densified monitoring stations[J]. Journal of Environmental Engineering Technology,2023,13(3):929-939. doi: 10.12153/j.issn.1674-991X.20221266 [8] SOULHAC L, PERKINS R J, SALIZZONI P. Flow in a street canyon for any external wind direction[J]. Boundary-Layer Meteorology,2008,126(3):365-388. doi: 10.1007/s10546-007-9238-x [9] LIU J R, CUI S H, CHEN G W, et al. The influence of solar natural heating and NO x-O3 photochemistry on flow and reactive pollutant exposure in 2D street canyons[J]. Science of the Total Environment,2021,759:143527. doi: 10.1016/j.scitotenv.2020.143527 [10] GROMKE C, RUCK B. Influence of trees on the dispersion of pollutants in an urban street canyon: experimental investigation of the flow and concentration field[J]. Atmospheric Environment,2007,41(16):3287-3302. doi: 10.1016/j.atmosenv.2006.12.043 [11] WANG X S, TENG M J, HUANG C B, et al. Canopy density effects on particulate matter attenuation coefficients in street canyons during summer in the Wuhan metropolitan area[J]. Atmospheric Environment,2020,240:117739. doi: 10.1016/j.atmosenv.2020.117739 [12] XUE F, LI X F. The impact of roadside trees on traffic released PM10 in urban street canyon: aerodynamic and deposition effects[J]. Sustainable Cities and Society,2017,30:195-204. doi: 10.1016/j.scs.2017.02.001 [13] 蒋昕, 钱长照, 陈昌萍. 篱墙对街谷中机动车排放CO扩散的影响研究[J]. 环境科学与技术,2021,44(11):48-54. [14] 杨柳. 基于交通流控制的城市交通环境颗粒物污染特征研究[D]. 北京: 清华大学, 2011. [15] 王嘉松, 黄震. 城市高架道路对局地大气环境影响的数值模拟研究[J]. 上海环境科学,2002,21(3):132-135. [16] HANG J, LIN M, WONG D C, et al. On the influence of viaduct and ground heating on pollutant dispersion in 2D street canyons and toward single-sided ventilated buildings[J]. Atmospheric Pollution Research,2016,7(5):817-832. doi: 10.1016/j.apr.2016.04.009 [17] DING S, HUANG Y D, CUI P Y, et al. Impact of viaduct on flow reversion and pollutant dispersion in 2D urban street canyon with different roof shapes: numerical simulation and wind tunnel experiment[J]. Science of the Total Environment,2019,671:976-991. doi: 10.1016/j.scitotenv.2019.03.391 [18] GROMKE C, JAMARKATTEL N, RUCK B. Influence of roadside hedgerows on air quality in urban street canyons[J]. Atmospheric Environment,2016,139:75-86. doi: 10.1016/j.atmosenv.2016.05.014 [19] SO E S P, CHAN A T Y, WONG A Y T. Large-eddy simulations of wind flow and pollutant dispersion in a street canyon[J]. Atmospheric Environment,2005,39(20):3573-3582. doi: 10.1016/j.atmosenv.2005.02.044 [20] GROMKE C, RUCK B. On the impact of trees on dispersion processes of traffic emissions in street canyons[J]. Boundary-Layer Meteorology,2009,131(1):19-34. doi: 10.1007/s10546-008-9301-2 [21] GALLAGHER J, GILL L W, McNABOLA A. Optimizing the use of on-street car parking system as a passive control of air pollution exposure in street canyons by large eddy simulation[J]. Atmospheric Environment,2011,45(9):1684-1694. doi: 10.1016/j.atmosenv.2010.12.059 [22] NAGPURE A S, GURJAR B R, KUMAR V, et al. Estimation of exhaust and non-exhaust gaseous, particulate matter and air toxics emissions from on-road vehicles in Delhi[J]. Atmospheric Environment,2016,127:118-124. doi: 10.1016/j.atmosenv.2015.12.026 [23] 王坚. 厦门市机动车排放因子研究[J]. 现代科学仪器,2005(6):61-64. doi: 10.3969/j.issn.1003-8892.2005.06.017WANG J. Research on the discharging factor of vehicles in Xiamen[J]. Modern Scientific Instruments,2005(6):61-64. doi: 10.3969/j.issn.1003-8892.2005.06.017 [24] MEI S J, LUO Z W, ZHAO F Y, et al. Street canyon ventilation and airborne pollutant dispersion: 2-D versus 3-D CFD simulations[J]. Sustainable Cities and Society,2019,50:101700. doi: 10.1016/j.scs.2019.101700 [25] TOMINAGA Y, STATHOPOULOS T. CFD modeling of pollution dispersion in a street canyon: comparison between LES and RANS[J]. Journal of Wind Engineering and Industrial Aerodynamics,2011,99(4):340-348. doi: 10.1016/j.jweia.2010.12.005 [26] GROMKE C, BUCCOLIERI R, di SABATINO S, et al. Dispersion study in a street canyon with tree planting by means of wind tunnel and numerical investigations: evaluation of CFD data with experimental data[J]. Atmospheric Environment,2008,42(37):8640-8650. doi: 10.1016/j.atmosenv.2008.08.019 [27] HE L J, HANG J, WANG X M, et al. Numerical investigations of flow and passive pollutant exposure in high-rise deep street canyons with various street aspect ratios and viaduct settings[J]. Science of the Total Environment,2017,584/585:189-206. doi: 10.1016/j.scitotenv.2017.01.138 [28] 田丰. 街道峡谷内机动车尾气扩散的数值模拟研究[D]. 广州: 中山大学, 2007. [29] ZHU J, LIU J, HE X, et al. Experimental study on the purification capacity of potted plants on low-concentration carbon monoxide in indoor environment[J]. Environmental Science and Pollution Research,2023,31(4):6316-6331. doi: 10.1007/s11356-023-31497-2 [30] 闰凌君. 汽车排放CO的植物净化研究[D]. 哈尔滨: 东北林业大学, 2007. □ -
下载:
点击查看大图
计量
- 文章访问数: 65
- HTML全文浏览量: 30
- PDF下载量: 30
- 被引次数: 0
