Item Details

Effect of Groundboard Height on the Aerodynamic Characteristics of a Lifting Circular Cylinder Using Tangential Blowing From Surface Slots for Lift Generation

by Vernard E. Lockwood
Format
Book; Government Document; Online; EBook
Published
Washington, [D.C.] : National Aeronautics and Space Administration, 1961.
Language
English
Series
NASA Technical Note
Summary
A wind-tunnel investigation has been made to determine the ground effect on the aerodynamic characteristics of a lifting circular cylinder using tangential blowing from surface slots to generate high lift coefficients. The tests were made on a semispan model having a length 4 times the cylinder diameter and an end plate of 2.5 diameters. The tests were made at low speeds at a Reynolds number of approximately 290,000, over a range of momentum coefficients from 0.14 to 4.60, and over a range of groundboard heights from 1.5 to 10 cylinder diameters. The investigation showed an earlier stall angle and a large loss of lift coefficient as the groundboard was brought close to the cylinder when large lift coefficients were being generated. For example, at a momentum coefficient of 4.60 the maximum lift coefficient was reduced from a value of 20.3 at a groundboard height of 10 cylinder diameters to a value of 8.7 at a groundboard height of 1.5 cylinder diameters. In contrast to this there was little effect on the lift characteristics of changes in groundboard height when lift coefficients of about 4.5 were being generated. At a height of 1.5 cylinder diameters the drag coefficients generally increased rapidly when the slot position angle for maximum lift was exceeded. Slightly below the slot position angle for maximum lift, the groundboard had a beneficial effect, that is, the drag for a given lift was less near the groundboard than away from the groundboard. The variation of maximum circulation lift coefficient (maximum lift coefficient minus momentum coefficient) obtained in this investigation is in general agreement with a theory developed for a jet-flap wing which assumes that the loss in circulation is the result of blockage of the main stream beneath the wing.
Description
23 p. : ill. ; 26 cm.
Mode of access: Internet.
Notes
  • Report Number: L-1521.
  • Document ID: 19980228161.
  • "NASA TN D-969."
  • "Langley Research Center, Langley Air Force Base, Va."
  • "October 1961."
  • Cover title.
  • Includes bibliographical references (p. 9).
Series Statement
NASA technical note ; D-969
Other Forms
Also available from the NASA Technical Reports Server (http://ntrs.nasa.gov/). Address as of 4/09/07: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980228161_1998388508.pdf.
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Technical Details

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    a| Effect of groundboard height on the aerodynamic characteristics of a lifting circular cylinder using tangential blowing from surface slots for lift generation / c| by Vernard E. Lockwood.
    260
      
      
    a| Washington, [D.C.] : b| National Aeronautics and Space Administration, c| 1961.
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    a| 23 p. : b| ill. ; c| 26 cm.
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    a| NASA technical note ; v| D-969
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    a| Report Number: L-1521.
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    a| Document ID: 19980228161.
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    a| "NASA TN D-969."
    500
      
      
    a| "Langley Research Center, Langley Air Force Base, Va."
    500
      
      
    a| "October 1961."
    500
      
      
    a| Cover title.
    504
      
      
    a| Includes bibliographical references (p. 9).
    520
      
      
    a| A wind-tunnel investigation has been made to determine the ground effect on the aerodynamic characteristics of a lifting circular cylinder using tangential blowing from surface slots to generate high lift coefficients. The tests were made on a semispan model having a length 4 times the cylinder diameter and an end plate of 2.5 diameters. The tests were made at low speeds at a Reynolds number of approximately 290,000, over a range of momentum coefficients from 0.14 to 4.60, and over a range of groundboard heights from 1.5 to 10 cylinder diameters. The investigation showed an earlier stall angle and a large loss of lift coefficient as the groundboard was brought close to the cylinder when large lift coefficients were being generated. For example, at a momentum coefficient of 4.60 the maximum lift coefficient was reduced from a value of 20.3 at a groundboard height of 10 cylinder diameters to a value of 8.7 at a groundboard height of 1.5 cylinder diameters. In contrast to this there was little effect on the lift characteristics of changes in groundboard height when lift coefficients of about 4.5 were being generated. At a height of 1.5 cylinder diameters the drag coefficients generally increased rapidly when the slot position angle for maximum lift was exceeded. Slightly below the slot position angle for maximum lift, the groundboard had a beneficial effect, that is, the drag for a given lift was less near the groundboard than away from the groundboard. The variation of maximum circulation lift coefficient (maximum lift coefficient minus momentum coefficient) obtained in this investigation is in general agreement with a theory developed for a jet-flap wing which assumes that the loss in circulation is the result of blockage of the main stream beneath the wing.
    530
      
      
    a| Also available from the NASA Technical Reports Server (http://ntrs.nasa.gov/). Address as of 4/09/07: http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19980228161_1998388508.pdf.
    538
      
      
    a| Mode of access: Internet.
    650
      
    7
    a| Wings. 2| nasat
    650
      
    7
    a| Semispan models. 2| nasat
    650
      
    7
    a| Wind tunnels. 2| nasat
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    a| Tangential blowing. 2| nasat
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    7
    a| Lift. 2| nasat
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    a| Coefficients. 2| nasat
    650
      
    7
    a| Ground effect (Aerodynamics) 2| nasat
    650
      
    7
    a| Circular cylinders. 2| nasat
    650
      
    7
    a| Aerodynamic characteristics. 2| nasat
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    1
      
    a| United States. b| National Aeronautics and Space Administration.
    710
    2
      
    a| Langley Research Center.
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    b| UIU c| UIUC d| 20141113 s| google u| uiug.30112106915090 y| 1961 r| pd q| bib

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