Development Study of a Two-Stage Continuous Flow Impactor.
TRW DEFENSE AND SPACE SYSTEMS GROUP REDONDO BEACH CA
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Two unit of a Continuous Flow Impactor CI were designed, constructed and tested. The units have been calibrated using DOP droplets and their fractionation points are approximately 4 and 1 micrometers for the first and second units respectively. The principal design criteria established in previous studies have been verified, and reshaping the collection chambers has proven effective in improving performance. The steepness of the cross-over efficiency of the 1st unit is comparable to that of other commercially available impactors. The performance of the 2nd unit is not as good though this is attributed to high particle loss in that unit. The two units have been operated in a cascade arrangement which separates an airborne window of a desired particle size range - between the fractionation points of the two stages - out of a polydispersed aerosol. The particle loss mechanisms are discussed and improvements are suggested to reduce the loss. Other potential applications of the CI such as in the separation of monodispersed aerosols, density measurement of spherical particles and shape factor determination are discussed as well.
- Civil Engineering
- Test Facilities, Equipment and Methods
- Fluid Mechanics