Particulate matter emission by an isolated rotating wheel

Particulate matter emission from rotating wheels, which imparts a force to the contact surface and causes strong air currents, is one of the important pollutant sources on the road. This study investigates the particulate matter emission by measuring mass and size distributions of particulate matter near an isolated rotating wheel in a deliberately designed setup. Five rotating speeds from 0.7 m/s to 1.5 m/s are conducted to test its impact on the emission of particulate matter. Mass of particulate matter is measured at twenty-six sampling points around the rotating wheel under different experimental conditions. Experimental results show that the farther away from the wheel, the less of particulate matters deposited on the sampling points in general. Moreover, the emission factor increases from 0.12 g/vkt to 0.24 g/vkt when the rotating speed of the wheel increases from 0.7 m/s to 1.5 m/s. The number and proportion of PM_2.5 and PM₁₀ on different sampling points are also measured. The results show that the position of the highest number of PM_2.5 and PM₁₀ tends to move to a further and higher sampling point with the increasing of the speed. Moreover, the number proportions of PM_2.5 and PM₁₀ on the sampling points range from 19% to 97% and 61% to 100% at different speeds, respectively. This study is believed to be helpful to estimate particulate matter emission and make effective control strategies on targeted pollution.