Item Details

Effect of Blockage Ratio on Drag and Pressure Distributions for Bodies of Revolution at Transonic Speeds

by Lana M. Couch and Cuyler W. Brooks, Jr.
Format
Book; Government Document; Online; EBook
Published
Washington, D.C. : National Aeronautics and Space Administration ; [Springfield, Va. : For sale by the National Technical Information Service], 1973.
Language
English
Series
NASA Technical Note
Summary
Experimental data were obtained in two wind tunnels for 13 models over a Mach number range from 0.70 to 1.02. Effects of increasing test-section blockage ratio in the transonic region near a Mach number of 1.0 included change in the shape of the drag curves, premature drag creep, delayed drag divergence, and a positive increment of pressures on the model afterbodies. Effects of wall interference were apparent in the data even for a change in blockage ratio from a very low 0.000343 to an even lower 0.000170. Therefore, models having values of blockage ratio of 0.0003 - an order of magnitude below the previously considered safe value of 0.0050 - had significant errors in the drag-coefficient values obtained at speeds near a Mach number of 1.0. Furthermore, the flow relief afforded by slots or perforations in test-section walls - designed according to previously accepted criteria for interference-free subsonic flow - does not appear to be sufficient to avoid significant interference of the walls with the model flow field for Mach numbers very close to 1.0.
Description
109 p. : ill. ; 27 cm.
Mode of access: Internet.
Notes
  • Prepared at Langley Research Center.
  • Cover title.
  • Bibliography: p. 18.
Series Statement
NASA technical note ; NASA TN D-7331
Logo for Copyright Not EvaluatedCopyright Not Evaluated
Technical Details

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    a| Effect of blockage ratio on drag and pressure distributions for bodies of revolution at transonic speeds c| by Lana M. Couch and Cuyler W. Brooks, Jr.
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    a| Washington, D.C. : b| National Aeronautics and Space Administration ; a| [Springfield, Va. : b| For sale by the National Technical Information Service], c| 1973.
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    a| 109 p. : b| ill. ; c| 27 cm.
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    a| NASA technical note ; v| NASA TN D-7331
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    a| Prepared at Langley Research Center.
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    a| Cover title.
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    a| Bibliography: p. 18.
    520
      
      
    a| Experimental data were obtained in two wind tunnels for 13 models over a Mach number range from 0.70 to 1.02. Effects of increasing test-section blockage ratio in the transonic region near a Mach number of 1.0 included change in the shape of the drag curves, premature drag creep, delayed drag divergence, and a positive increment of pressures on the model afterbodies. Effects of wall interference were apparent in the data even for a change in blockage ratio from a very low 0.000343 to an even lower 0.000170. Therefore, models having values of blockage ratio of 0.0003 - an order of magnitude below the previously considered safe value of 0.0050 - had significant errors in the drag-coefficient values obtained at speeds near a Mach number of 1.0. Furthermore, the flow relief afforded by slots or perforations in test-section walls - designed according to previously accepted criteria for interference-free subsonic flow - does not appear to be sufficient to avoid significant interference of the walls with the model flow field for Mach numbers very close to 1.0.
    538
      
      
    a| Mode of access: Internet.
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    a| Aerodynamics, Transonic.
    650
      
    0
    a| Body of revolution.
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    0
    a| Aerodynamic load.
    650
      
    0
    a| Interference (Aerodynamics)
    650
      
    0
    a| Drag (Aerodynamics)
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    1
      
    a| Brooks, Cuyler W.
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    a| United States. b| National Aeronautics and Space Administration.
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    a| Langley Research Center.
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