Aeroacoustics of Supersonic Elliptic Jets

TITLE AND SUBTITLE:
Aeroacoustics of Supersonic Elliptic Jets

AUTHOR(S):
Abbas Khavaran and Nicholas J. Georgiadis

REPORT DATE:
January 1996

FUNDING NUMBERS:
WU-538-03-11

PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Lewis Research Center
Cleveland, Ohio 44135-3191

PERFORMING ORGANIZATION REPORT NUMBER:
E-10081

SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES):
National Aeronautics and Space Administration
Washington, D.C. 20546-0001

REPORT TYPE AND DATES COVERED:
Technical Memorandum

SPONSORING/MONITORING AGENCY REPORT NUMBER:
NASA TM-107148
AIAA-96-0641

SUPPLEMENTARY NOTES:
Prepared for the 34th Aerospace Sciences Meeting and Exhibit sponsored by the American Institute of Aeronautics and Astronautics, Reno, Nevada, January 15-18, 1996. Abbas Khavaran, NYMA, Inc., 2001 Aerospace Parkway, Brook Park, Ohio 44142 (work funded by NASA Contract NAS3-27186); and Nicholas J. Georgiadis, NASA Lewis Research Center. Responsible person, Nicholas J. Georgiadis, organization code 2740, (216) 433-3958.

ABSTRACT:
The sound field due to a supersonic elliptic jet is studied by direct integration of the propagation equations. Aerodynamic predictions are based on numerical solution to the compressible Navier-Stokes equations in conservative law form, with a k-e turbulence model. In the high frequency limit, the sound field is described by eigenrays that link the source of noise to an observer in the far-field. We assume that noise is dominated by fine-scale turbulence. Using methods derived from acoustic analogy, source correlation terms are simplified and a model is derived that relates jet noise intensity to the 7/2 power of turbulence kinetic energy. Local characteristics of the source such as its strength, time- or length-scale, and convection velocity are derived from mean flow predictions. Numerical results are compared with data for a Mach 1.5 elliptic jet as well as for a round jet. The study suggests that three-dimensional directivity of noise for jets of arbitrary geometry may be predicted with reasonable accuracy when refraction by mean flow gradients is properly accounted for.

SUBJECT TERMS:
Aeroacoustics; Jet noise; Aerodynamic noise

NUMBER OF PAGES:
15

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