Development of a Sampling Probe for Representative Sampling of PM at Freestream Velocities in the Range from 0 to 300 km h−1

Abstract

To accurately forecast the concentrations of fine and thoracic coarse particles [particulate matter (PM) 2.5 and 10, respectively], it is important to secure a large number of boundary conditions. For this purpose, particle concentrations need to be measured not only at predefined observatory sites but also in more regions. Various types of vehicles can be used for collecting ambient aerosol not only on the ground but also in the air, and thus it is necessary to use specially designed sampling probes that enable efficient sampling of particles in variable airstream velocity conditions. This study developed a double-shrouded probe as a representative sampling probe available within a range of stream velocity from 0 to 300 km h−1. An additional shroud was added to the outer face of a single-shrouded probe, and an annular tapered wing was added to a sampling tube. Numerical analyses and experiments were performed, and their results were compared. The double-shrouded probe was found to be appropriate for representative sampling of PM2.5 and PM10 at velocities of 300 km h−1 or less and 150 km h−1 or less, respectively, which are significantly extended compared to the range of the currently possible velocity for the single-shrouded probe. The double-shrouded probe onboard various types of air or land vehicles is expected to contribute to accurate measurements of PM concentration under the condition of a high-speed stream.