EFFECT OF FORWARD MOTION ON ENGINE NOISE

Methods used to determine a procedure for correcting static engine data for the effects of forward motion are described. Data were analyzed from airplane flyover and static-engine tests with a JT8D-109 low-bypass-ratio turbofan engine installed on a DC-9-30, with a CF6-6D high-bypass-ratio turbofan engine installed on a DC-10-10, and with a JT9D-59A high-bypass-ratio turbofan engine installed on a DC-10-40. The observed differences between the static and the flyover data bases are discussed in terms of noise generation, convective amplification, atmospheric propagation, and engine installation. The results indicate that each noise source must be adjusted separately for forward-motion and installation effects and then projected to flight conditions as a function of source-path angle, directivity angle, and acoustic range relative to the microphones on the ground.

  • Corporate Authors:

    Douglas Aircraft Company, Incorporated

    3855 Lakewood Boulevard
    Long Beach, CA  USA  90801
  • Authors:
    • Blankenship, G L
    • Low, JKC
    • Watkins, J A
    • Merriman, J E
  • Publication Date: 1977-10

Media Info

  • Pagination: 198 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00174597
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NASA-CR-134954, MDC-J7708
  • Contract Numbers: NAS3-20031
  • Files: TRIS
  • Created Date: Mar 14 1978 12:00AM