An Experimental Investigation of the Flow in a Virtual Cyclone

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An experimental investigation has confirmed the predicted flow pattern in a prototype virtual cyclone, a novel device for nonimpact particle separation proposed by Torcdzynski and Rader (1996, 1997) based solely on computational simulations. The virtual cyclone differs from an ordinary cyclone in that the flow is turned by a virtual wall composed of an eddy rather than by a solid wall. A small-scale version of the computationally simulated geometry has been fabricated out of Lucite. The working fluid is ambient air, which is drawn through the apparatus and flow-metering equipment using a wind-tunnel vacuum source. The flow is seeded with ... continued below

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44 p.

Creation Information

Torczynski, J.R.; O'Hern, T.J.; Rader, D.J.; Brockmann, J.E. & Grasser, T.W. September 1, 1998.

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  • Sandia National Laboratories
    Publisher Info: Sandia National Labs., Albuquerque, NM (United States)
    Place of Publication: Albuquerque, New Mexico

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Description

An experimental investigation has confirmed the predicted flow pattern in a prototype virtual cyclone, a novel device for nonimpact particle separation proposed by Torcdzynski and Rader (1996, 1997) based solely on computational simulations. The virtual cyclone differs from an ordinary cyclone in that the flow is turned by a virtual wall composed of an eddy rather than by a solid wall. A small-scale version of the computationally simulated geometry has been fabricated out of Lucite. The working fluid is ambient air, which is drawn through the apparatus and flow-metering equipment using a wind-tunnel vacuum source. The flow is seeded with smoke or water droplets produced by a nebulizer so that flow visualization techniques and particle-imaging velocimetry could be applied. Experiments have been performed on this apparatus for flows with Reynolds numbers from 200 up to 40,000 (a Mach number of 0.3). Flow visualization using a laser light sheet passing through the mid-plane of the apparatus verified that the computationally predicted flow is obtained over the entire range of flow rates. The shear layer between the main and recirculating flow is observed to become turbulent around a Reynolds number of 4000. While not changing the flow structure, the turbulent mixing produced by shear-layer roll-up limits particle concentration at the higher flow rates. In order to achieve highly efficient particle separation using a virtual cyclone, turbulence must be suppressed or mitigated. If laminar flow cannot be achieved for macroscopic-scale virtual cyclones, it should be achievable for a small-scale (low Reynolds number) virtual cyclone fabricated using MEMS-related technologies. This approach could lead to a chip-scale particle concentrator.

Physical Description

44 p.

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OSTI as DE00001315

Medium: P; Size: 44 pages

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  • No conference title supplied, No conference location supplied, No conference dates supplied

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  • Report No.: SAND98-2004
  • Report No.: YN010000000
  • Grant Number: AC04-94AL85000
  • Office of Scientific & Technical Information Report Number: 1315
  • Archival Resource Key: ark:/67531/metadc625310

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Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

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  • September 1, 1998

Added to The UNT Digital Library

  • June 16, 2015, 7:43 a.m.

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  • April 12, 2017, 4:40 p.m.

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Torczynski, J.R.; O'Hern, T.J.; Rader, D.J.; Brockmann, J.E. & Grasser, T.W. An Experimental Investigation of the Flow in a Virtual Cyclone, article, September 1, 1998; Albuquerque, New Mexico. (digital.library.unt.edu/ark:/67531/metadc625310/: accessed November 21, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.