The need to aerodynamically remove isolated charged particles 50 to 500 micrometers in size from a bed comprised of numerous smaller 10-15 micrometers size charged particles is identified. To facilitate accurate prediction for successful particle removal, a new analytical method is presented for determining the magnitude and location of the aerodynamic drag force acting on a spherical particle in a boundary layer flow. Wind tunnel experiments are conducted on spheres of 2 to 2.5 cm diameter in turbulent boundary layer flow for sphere Reynolds numbers on the order of 10,000. The experiments measure the drag force on the sphere and the flow velocity profile at the point of incipient motion of the sphere. The test, results obtained in the wind tunnel experiment compare favorably to predictions of the analytical method presented. This method is extended to analyze the onset of incipient motion for the 50 to 500 micrometers agglomerate particles subject to the drag forces induced by a vacuum nozzle and the adhesion forces caused by electrostatic charge on the particles. The analysis is modeled in an interactive computer program. The effects of air velocity, particle size, charge and shape, and the ratio of lift to drag forces on the threshold of predicted particle removal are determined and discussed. Additional experiments involving the vacuum nozzle applied to particles in eight different size classes ranging from 15 to 500 micrometers are conducted. Difficulties in controlling the charge level of the particles required that uncharged particles be tested. Experimental results based on observed weight percentage removal of the particles for the eight different size classes compare favorably to removal likelihood as predicted by the analysis.
Library of Congress Subject Headings
Drag (Aerodynamics)--Research--Analysis; Particles--Research--Analysis; Electrophotography--Research--Analysis; Copying machines--Design--Analysis
Department, Program, or Center
Mechanical Engineering (KGCOE)
Bothner, Carl, "Analytical study of the aerodynamic removal of small, charged particles from a dielectric surface" (1988). Thesis. Rochester Institute of Technology. Accessed from
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