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Influence and Its Simulation of Vehicular Exhaust on the Air Quality in the Street

Author: ShiXiaoPeng
Tutor: XiangRongBiao；LiuFan
School: Huazhong Agricultural University
Course: Environmental Engineering
Keywords: City streets Vehicle exhaust CO pollution Traffic flow Numerical Simulation Indoor air quality
CLC: X51
Type: Master's thesis
Year: 2008
Downloads: 316
Quote: 0
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Abstract

With the accelerated process of China's urbanization and industrialization, China's large cities vehicle ownership in recent years the rapid growth and bring prosperity to our economy at the same time, also caused serious pollution of urban atmospheric environment. Currently, motor vehicle emissions of pollutants recognized as the main sources of pollution of the ambient air of the city streets, and has confirmed that its street construction indoor air quality will have a serious impact. Must to conduct a comprehensive study of the relationship between the Motor Vehicle Pollution the diffusion laws frontage building indoor and outdoor air quality, in order to evaluate Street motor vehicle pollution, prediction and control of indoor air quality as well as the urban road planning to provide a scientific basis. This study as the research object the the typical main roads and secondary roads in Wuhan, the measured CO concentration in the street, and analysis of traffic conditions, weather factors, geographical conditions and other factors that impact on the dispersion of pollutants; simultaneously using computational fluid dynamics CFD street canyon model for the simulation of the wind field and pollutant concentration field, in order to establish the appropriate numerical simulation method can be used to forecast street canyon pollutant concentration, general law affect the diffusion factors analysis and simulation data; addition, the indoor street construction outside the CO concentration measured analysis of the impact of traffic pollution on indoor air pollution law. Street canyon measurements and analysis show that: have a significant impact on traffic flow, wind speed, temperature, and aspect ratio of the diffusion and distribution of CO concentration. The concentration of pollutants with the traffic flow into positive correlation, negative correlation with the wind speed, temperature into. The analysis can be seen on the street structure: street aspect ratio is the most important factors affecting the diffusion, and the aspect ratio of the larger, more is not conducive to proliferation, the higher the concentration of pollutants. Derived CO concentration distribution analysis of the intersection, the intersection of the most heavily polluted, the upwind pollution lighter rational arrangement of the angle of intersection can improve the pollution situation. Data Simulation results show that: the CFD model can be applied to the simulation of the pollutant concentration in the street canyon. Standard k-ε model is the proportion of the whole group (RNG) k-ε model is more suitable for the simulation of street canyon wind farm. Simulation of the concentration field a little bit better than in the leeward side of the standard k-ε model simulation RNGk-ε model, slightly better than the standard k-ε model in the windward side RNGk-ε model simulation. Wind speed, height of the high aspect ratio on the diffusion of pollutants through simulation results are obtained negative correlation trend of the concentration of pollutants with the wind velocity pollutant concentration as the wind speed increases, the increase in height, high aspect ratio reduce lower; analyze a different aspect ratio leeward and windward side of the pollutant concentration differences found high aspect ratio affects the flow field distribution, thereby affecting the concentration of pollutants in the back of the leeward side and the windward side of the distribution. The simulation results can better explain the the actual street distribution of environmental pollutants law. Outdoor pollution on indoor pollution, by analyzing the monitoring data of the the street building indoor and outdoor CO concentration, next to the outdoor CO concentration is significantly larger than the impact on the indoor concentration away from the trunk road beside the trunk road outdoor concentrations of indoor concentration impact. Indoor concentrations and outdoor concentrations significantly delayed effects. Obviously, the health personnel in the the street building indoor work by the threat of the motor vehicle emissions of pollutants.

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