A basic understanding of the noise reduction mechanisms in shock-free inverted-velocity-profile coannular jets was studied. Acoustic measurements are first conducted in an anechoic facility to isolate the effects of inverted velocity and inverted temperature for coannular jets having constant total thrust, mass flow rate and exit area. To obtain physical explanations of the measured noise changes, several types of experiments are conducted. These include (1) source location experiments using the polar correlation technique, (2) mean flow surveys using a combination pressure/temperature probe, and (3) detailed mean flow and turbulence measurements using a two-point four-channel laser velocimeter. The results from these experiments are presented and discussed in detail. Finally, the measured variations of coannular jet mixing noise with fan-to-primary velocity ratio and static temperature ratio are interpreted by utilizing the results from the various experimental phases in conjunction with the existing Lockheed single jet noise prediction model.

  • Corporate Authors:

    Lockheed-Georgia Company

    Marietta, GA  United States 
  • Authors:
    • Tanna, H K
    • Tester, B J
    • Lau, J C
  • Publication Date: 1979-2

Media Info

  • Pagination: 382 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00197932
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NASA-CR-158995
  • Contract Numbers: NAS1-15018
  • Files: TRIS
  • Created Date: Sep 15 1979 12:00AM