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  • 1975-1979  (4)
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  • 1
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    Unknown
    An experimental evaluation of the application of the Kirchhoff formulation for sound radiation from an oscillating airfoil (1977)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: The Kirchhoff integral formulation is evaluated for its effectiveness in quantitatively predicting the sound radiated from an oscillating airfoil whose chord length is comparable with the acoustic wavelength. A rigid airfoil section was oscillated at samll amplitude in a medium at rest to produce the sound field. Simultaneous amplitude and phase measurements were made of surface pressure and surface velocity distributions and the acoustic free field. Measured surface pressure and motion are used in applying the theory, and airfoil thickness and contour are taken into account. The result was that the theory overpredicted the sound pressure level by 2 to 5, depending on direction. Differences are also noted in the sound field phase behavior.
    Keywords: ACOUSTICS
    Type: NASA-TP-1048 , L-11479
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    Feasibility of making sound power measurements in the NASA Langley V/STOL tunnel test section (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Based on exploratory acoustic measurements in Langley's V/STOL wind tunnel, recommendations are made on the methodology for making sound power measurements of aircraft components in the closed tunnel test section. During airflow, tunnel self-noise and microphone flow-induced noise place restrictions on the amplitude and spectrum of the sound source to be measured. Models of aircraft components with high sound level sources, such as thrust engines and powered lift systems, seem likely candidates for acoustic testing.
    Keywords: ACOUSTICS
    Type: NASA-TM-X-73934
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 3
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    Unknown
    Investigation of trailing-edge noise (1979)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: A comprehensive experimental investigation of airfoil trailing-edge noise up to a Reynolds number based on chord of 2.96 x 10 to the 6th power is described. Comparisons are made with current theory, particularly with regard to the pressure field in the vicinity of the trailing-edge and its influence on the radiated noise.
    Keywords: ACOUSTICS
    Type: Mechanics of sound generation in flows; Aug 28, 1979 - Aug 31, 1979; Goettingen
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Unknown
    An experimental investigation of trailing-edge noise (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Airfoil trailing-edge noise up to a Reynolds number based on chord of 2.96 x 10 to the 6th power was studied. Comparisons are made with current theory, particularly with regard to the nature of the pressure field in the vicinity of the trailing-edge and its influence on the radiated noise.
    Keywords: ACOUSTICS
    Type: NASA-TM-80134
    Format: application/pdf
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    NASA TECHNICAL REPORTS
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