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The flow characteristics and particle collection efficiencies of a long-cone cyclone with twice as long a conical section as that of the Stairmand cyclone were analyzed numerically to see the effect of the cylinder shape on the flow and collection performance. The three-dimensional flow field is obtained using the commercial package, FLUENT, and particle paths are calculated with the Lagrangean integration of the particle equation of motion. A number of turbulence models were tested, and it was confirmed that only the second-order Reynolds stress model gave reasonable results for the flow velocity profile. It is also shown that the shape of the core-annulus interface is important for the overall flow and collection characteristics, and the interface shape is in turn strongly affected by the distance from the bottom of the inlet to the cylinder-cone junction. By adjusting the diameters of the cylinder and the view finder with the mass flux and inlet area kept constant, the shape of the core-annulus interface could be changed. As a result, the short-circuiting of the inlet flow to the view finder and the total pressure drop could be reduced by properly adjusting the cylinder body diameter. |
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