The Aerosol Classification Performance of a Rectangular Jet Virtual-Impactor [Translated]†

Abstract

The aerosol classification performance of a newly constructed rectangular jet virtual-impactor has been studied both theoretically and experimentally. It is found that the performance is well represented by potential flow calculations with modifications for the effects of the acceleration jet and flow separation at the slit. The sharpness of the classification is not as good as that of a round jet impactor, and the variable range of the cut size is smaller. In the rectangular jet impactor, however, a higher flow rate of aerosol can be treated without changing the cut size. It is also found that higher degrees of sharpness are obtained and that the cut size is variable within a certain range by introducing clean air flows as in the round jet impactor previously developed by the authors. The separation characteristic is found to be well explained by assuming perfect mixing between the aerosol flow and the clean-air flows at both ends of the rectangular jet. The maximum inertia parameter limited by the sound velocity is also discussed, and an empirical equation representing the pressure drop of the impactor is presented.† This report was originally printed in KAGAKU KOGAKU RONBUNSHU, 10(5), 561-567 (1984) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Chemical Engineers, Japan.