Screw-generated forces in granular media: Experimental,computational, and analytical comparison |
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Authors: | Andrew Thoesen Sierra Ramirez Hamid Marvi |
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Affiliation: | School for Engineering of Matter, Transport and Energy (SEMTE), Arizona State University, Tempe, AZ 85251 |
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Abstract: | This study presents an experimental, computational, and analytical comparison of a submerged, double-helix Archimedes screw generating propulsive force against a bed of glass beads. Three screws of different pitch lengths were studied. Each screw was tested at six speeds in approximately 10 trials for a total of 180 experimental trials. These experiments were then replicated in EDEM, a discrete element method (DEM) software program. DEM simulation results for thrust forces in the 30–120 rpm regime had a 5%–20% inflation of forces compared to experimental results. These simulations were then compared with resistive force theory (RFT) plate approximation of the screw geometries. We analyze a superposition-based partition approach to the full-length screws as well as force generation in shortened, one- and two-blade screws. We find that the force generation is dependent on the flow patterns and cannot be reduced to partitioned approximations as with simple intruders. © 2018 American Institute of Chemical Engineers AIChE J, 65: 894–903, 2019 |
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Keywords: | granular media discrete element method resistive force theory screw |
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