Anisokinetic sampling of aerosols at a slot intake

The flow at intake to some aerosol samplers may be regarded as two-dimensional flow into a thin-walled slot. A theoretical analysis is given of the efficiency with which such a slot collects particles from an approaching gas flow for the case where the approach velocity exceeds the mean velocity in the intake. In the theory, which takes regions of separated flow into account, the gas flow is treated as a potential flow and Stokes law is assumed to govern the interaction between particles and gas. Curves of calculated collection efficiency are given over a wide range of Stokes number for ratios of approach velocity to mean intake velocity up to 20. Where Stokes law is not applicable the collection efficiency obtained from the curves is an upper limiting value. © 1980.