不同排气管设计参数下汽车尾部颗粒物排放扩散模拟分析

AbstractThe analysis of air pollution sources shows that motor vehicles have becomethe main source of air pollution in key urban areas.Major countries and regionsin the world have tightened emission regulations to reduce the environmentalpollution caused by motor vehicles.In recent years,with the improvement ofpeople's living standards,more and more people choose the way of self driving,which plays a certain role in stimulating economic growth.In many fields,thereare also diesel engines,such as agricultural machinery,engineering machinery,marine machinery,etc.,which bring a lot of benefits to people's life.However,the pollution of particulate matter and nitrogen oxides from motor vehicles isbecoming more and more serious.Therefore,it is particularly important tounderstand the emission diffusion characteristics of vehicle exhaust particles.In this paper,the two-dimensional models of exhaust pipes with differentdiameters and exhaust directions are established in gambit and meshed,and thenimported into fluent,combined with their own knowledge and simulation analysismethod,to study the emission and diffusion characteristics of particulatematter in the tail of automobile exhaust pipe under different design parameters.Conclusion:when the height and inclination of the exhaust pipe are the same,the different diameter of the exhaust pipe will affect the diffusion ofparticulate matter.When the diameter of the exhaust pipe is larger,the velocityof particles is larger and the diffusion range is larger.The direction of exhaustpipe also affects the diffusion of PM2.5.When the tail gas pipe inclines upward,compared with the horizontal direction,the tail gas is discharged upward,andthe flow field is higher,which makes the particles suspended in the air fora long time,so the residence time of PM2.5 in the air becomes longer;When theexhaust pipe inclines downward,compared with the horizontal direction,the flowfield is lower,which makes PM2.5 easy to settle and accumulate.Under the samepipe diameter,with the increase of the height of the exhaust pipe above theground,the diffusion range of the exhaust gas will become larger.Keywords:Particulate matter,diffusion,fluent,exhaust pipeII