A Couette-Taylor Size Classifier for Coarse, Airborne Particles

78167S05 Airborne particles significantly influence the radiative budget of the earth's atmosphere through direct scattering and absorption of solar and thermal infrared radiation, and through modification of the earth's cloud cover. Important to these effects is the aerosol size distribution and the aerosol hygroscopicity. Better measurements are needed for both of these parameters in particle size ranges larger than that spanned by current mobility systems, namely, for particle diameters greater than 0.5 ¿m. This project will develop a particle size classifier based on aerodynamic balancing within a Couette-Taylor flow. Phase I will design, construct, and conduct laboratory tests of the Couette Taylor Particle Size Classifier. Specific objectives are to assess the precision of size selection, the transmission efficiency of the selected size, and the extent to which these parameters can be described from first principles. Commercial Applications and Other Benefits as described by the awardee: The particle size classifier, designed for the particle size range above 0.5 ¿m, should be comparable in function to the differential mobility analyzers now used for size selection of smaller particles. Commercial applications should include instrument calibration, laboratory experiments, and ambient aerosol measurements.