Diffusion of vehicle exhaust fumes

Abstract

Diffusion of motor vehicle exhaust fumes is a function of not only the type of fuel and vehicle age but also of the vehicle movement, atmospheric wind, turbulence and thermal stability. Two methods are used to examine these effects on the diffusion of the exhaust fumes: direct probing by means of road tests using a full-scale system and wind tunnel tests using a model. Field tests have been conducted at the Meteorological Field Station at Woodbridge. The tests include a common stationwagon. A meteorological instrumented tower was used at the test site. Attention was given to the flow of the exhaust fumes by observing and photographically recording their entrainment and modification by the ground, wind speed and thermal stability. Motor vehicle aerodynamics were studied in a specially designed wind tunnel. Streamlines passing over the roof of the vehicle swept down to the ground level and then divided to form a series of vortices. These in turn helped to elevate the exhaust fumes to a height which depends on the vehicle size. © Taylor & Francis Group, LLC.