The results of the investigation of the noise characteristics of the exhaust jets from coannular nozzles with conventional and inverted velocity profiles are presented. Experiments were carried out on a series of coannular nozzles of equal primary and secondary area. The majority of acoustic tests were carried out holding either the total thrust or the total mass flow constant while varying the rates of secondary velocity to primary velocity. A limited number of tests were also made simulating the takeoff, cutback and approach conditions of the JT8D engine and corresponding inverted conditions. The results of this study show that at high thrust level the coannular flows with inverted velocity profiles are quieter than those with standard velocity profiles at the same thrust and the same mass flow. The acoustic differences are much greater when the velocity ratio is produced by differences in the stagnation temperature rather than by differences in the stagnation pressure. (Author)

  • Supplemental Notes:
    • See also Rept. no. FAA-RD-75-162 Volumes 1 thru 3, AD-A024 958, AD-A024 959 and AD-A041 782.
  • Corporate Authors:

    University of Tennessee, Tullahoma

    Space Institute, 411 BH Goethert Parkway
    Tullahoma, TN  United States  37388-9700
  • Authors:
    • Goethert, B H
    • Maus, J R
    • Dunnill, W A
    • Dathe, I
    • Venkitarama, S
  • Publication Date: 1978-4

Media Info

  • Pagination: 140 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00190564
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: FAA-RD-78-32 Final Rpt
  • Contract Numbers: DOT-FA72WA-3053
  • Files: NTIS, TRIS
  • Created Date: Mar 14 1979 12:00AM