Item Details

An Improved Method for Design of Expansion-Chamber Mufflers With Application to an Operational Helicopter

by Tony L. Parrott
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
An improved method for the design of expansion-chamber mufflers is described and applied to the task of reducing exhaust noise generated by a helicopter. The method is an improvement of standard transmission-line theory in that it accounts for the effect of the mean exhaust-gas flow on the acoustic-transmission properties of a muffler system, including the termination boundary condition. The method has been computerized, and the computer program includes an optimization procedure that adjusts muffler component lengths to achieve a minimum specified desired transmission loss over a specified frequency range. A printout of the program is included together with a user-oriented description.
Description
71 p. : ill. ; 27 cm.
Mode of access: Internet.
Notes
  • Prepared at Langley Research Center.
  • Cover title.
  • Bibliography: p. 52-53.
Series Statement
NASA technical note ; NASA TN D-7309
Logo for Copyright Not EvaluatedCopyright Not Evaluated
Technical Details

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    a| An improved method for design of expansion-chamber mufflers with application to an operational helicopter c| by Tony L. Parrott.
    260
      
      
    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| 71 p. : b| ill. ; c| 27 cm.
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    a| NASA technical note ; v| NASA TN D-7309
    500
      
      
    a| Prepared at Langley Research Center.
    500
      
      
    a| Cover title.
    504
      
      
    a| Bibliography: p. 52-53.
    520
      
      
    a| An improved method for the design of expansion-chamber mufflers is described and applied to the task of reducing exhaust noise generated by a helicopter. The method is an improvement of standard transmission-line theory in that it accounts for the effect of the mean exhaust-gas flow on the acoustic-transmission properties of a muffler system, including the termination boundary condition. The method has been computerized, and the computer program includes an optimization procedure that adjusts muffler component lengths to achieve a minimum specified desired transmission loss over a specified frequency range. A printout of the program is included together with a user-oriented description.
    538
      
      
    a| Mode of access: Internet.
    650
      
    0
    a| Helicopters x| Noise.
    650
      
    0
    a| Airplanes x| Motors x| Mufflers x| Design and construction x| Computer programs.
    650
      
    0
    a| Airplanes x| Motors x| Mufflers x| Design and construction.
    710
    1
      
    a| United States. b| National Aeronautics and Space Administration.
    710
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    a| Langley Research Center.
    974
      
      
    b| UIU c| UIUC d| 20141113 s| google u| uiug.30112106885657 y| 1973 r| pd q| bib

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