Research On The Distribution Of Vehicle Exhaust Diffusion On Urban Roads

Under the background of increasingly serious environmental pollution and the rapid increase of car ownership,the pollution caused by automobile exhaust has been widely concerned.These exhaust gases diffuse into the city.Due to the characteristics of semi closed space in the city,the exhaust gas can not be discharged in time,which affects the health of residents.In the city,the height width ratio of buildings and streets,the height difference of buildings in front and back row,the height difference of buildings on both sides of the street,wind direction and other factors may affect the diffusion of pollutants.In this paper,CFD diffusion model is selected to simulate the diffusion distribution of automobile exhaust under complex urban environment,and the influence degree of these factors on the diffusion of exhaust gas is studied.The main research contents include the following aspects:Firstly,the paper selects the diffusion model which is suitable for the city at present.Considering the complexity of the city space and the diversity of the research factors,the paper selects the CFD diffusion model with stronger adaptability,and explains the simulation process and relevant parameters of the emission and diffusion model in detail.Secondly,the paper chooses to build a three-dimensional model with reference to Guangji South Road,and collects information such as building height,street width,traffic flow and vehicle type distribution,prevailing wind direction,climate and environment.The building height and street width in the model are consistent with the actual situation of the selected road,and then simulate the diffusion of automobile exhaust pollutants from the micro scale.In this paper,an idealized street with height width ratio of 0.5:1,1:1,1.5:1 and 2:1 buildings on both sides is established.At the same time,there are three complex forms of street Valley,such as the height difference between the buildings on both sides of the street,the intersection between the two buildings,and the height difference between the front and rear buildings.Finally,the paper uses carbon monoxide(CO)as the pollutant diffusion material,uses CFD to study the influencing factors of carbon monoxide diffusion,analyzes which factors have the most obvious influence on the distribution law,and puts forward some suggestions for the cross-section layout of urban roads,and some index ranges for the construction height of buildings.This paper provides a theoretical basis for the study of the distribution of pollutants in complex street structures,and can be a powerful tool for the departments concerned to understand the influencing factors of automobile exhaust pollution on urban roads and formulate pollution control countermeasures.It has good scientific research applications and practical value.