Jet-Cone Impactors as Aerosol Particle Separators

A jet-cone impactor, designed to eliminate particle bounce and reentrainment of collected aerosol material and to collect larger samples for analysis by removing impacted material to a secondary collection region with a portion of the gas flow, was calibrated experimentally for impaction surface angles of 45° and 60°. Collection efficiencies were also calculated for a model impactor flow to determine effects of changing the impaction surface angle and jet Reynolds number. Sharpness of separation increased with increasing impaction surface angle, and impactor cut size decreased with increasing impaction surface angle. Variation of jet Reynolds number over a tenfold range had little effect on collection efficiency. Since agreement between experiment and theory was quite good, calculated collection efficiencies are recommended as a standard for this type of impactor.