Noise reduction by interaction of flexible filaments with an underexpanded supersonic jet

Bruce A. Anderson, Israel J Wygnanski, Ephraim J. Gutmark

Research output: Chapter in Book/Report/Conference proceedingConference contribution

18 Citations (Scopus)

Abstract

Experiments were conducted at Boeing Interior Noise Test Facility (INTF) to evaluate the reduction of jet noise by a small diameter cord in a cold underexpanded jet plume. Different cord diameters, lengths and styles were used to determine the optimum configuration. The optimized configuration of the cord was multi-stranded Kevlar fibers, 3 jet diameters long and having thickness of 2% of the jet diameter. A small knot at the downstream tip of the cord stabilized it along the jet centerline. The tests were performed using a single jet and coaxial cold coflowing jets. The primary jet velocity was M=1.2, and the secondary flow was set at M=0 or 0.876. Acoustic and flow visualization data showed substantial decrease of the jet noise and a significant change in the flow structure. The shock waves present in the core of the underexpanded jet were weakened and helical structures in the shear layer were suppressed. The strongest effect observed was the complete suppression of the screech tones and reduction of up to 30 dB in the shock-associated noise. This effect was stronger in the single jet than in the coaxial jet and was most noticeable in the region perpendicular to the jet at the nozzle plane. A substantial decrease of the turbulent mixing noise was obtained in the entire range of measured frequencies up to 40 kHz. This effect was most pronounced in the aft region of the jet. The filament changed both the magnitude and directivity of the sound emission. The distribution of the far field Sound Pressure Level became nearly uniform, with predominant perpendicular orientation. This paper presents an effective technique for jet noise reduction which is easy to implement and which does not carry heavy penalty in extra dead weight, loss of thrust and reduced propulsion efficiency. The technique was shown to be most effective for the underexpanded jet flow conditions described in this paper. However, tests were also performed in high subsonic single and coaxial jets and in heated jet flows. In all cases certain degree of turbulent mixing noise reduction was recorded.

Original languageEnglish (US)
Title of host publication37th Aerospace Sciences Meeting and Exhibit
PublisherAmerican Institute of Aeronautics and Astronautics Inc, AIAA
StatePublished - 1999
Event37th Aerospace Sciences Meeting and Exhibit, 1999 - Reno, United States
Duration: Jan 11 1999Jan 14 1999

Other

Other37th Aerospace Sciences Meeting and Exhibit, 1999
CountryUnited States
CityReno
Period1/11/991/14/99

Fingerprint

Noise abatement
noise reduction
filaments
interactions
jet aircraft noise
turbulent mixing
jet flow
screech tones
Kevlar (trademark)
secondary flow
acoustics
flow visualization
shear layers
directivity
test facilities
sound pressure
propulsion
configurations
penalties
thrust

ASJC Scopus subject areas

  • Space and Planetary Science
  • Aerospace Engineering

Cite this

Anderson, B. A., Wygnanski, I. J., & Gutmark, E. J. (1999). Noise reduction by interaction of flexible filaments with an underexpanded supersonic jet. In 37th Aerospace Sciences Meeting and Exhibit [AIAA 99-0080] American Institute of Aeronautics and Astronautics Inc, AIAA.

Noise reduction by interaction of flexible filaments with an underexpanded supersonic jet. / Anderson, Bruce A.; Wygnanski, Israel J; Gutmark, Ephraim J.

37th Aerospace Sciences Meeting and Exhibit. American Institute of Aeronautics and Astronautics Inc, AIAA, 1999. AIAA 99-0080.

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Anderson, BA, Wygnanski, IJ & Gutmark, EJ 1999, Noise reduction by interaction of flexible filaments with an underexpanded supersonic jet. in 37th Aerospace Sciences Meeting and Exhibit., AIAA 99-0080, American Institute of Aeronautics and Astronautics Inc, AIAA, 37th Aerospace Sciences Meeting and Exhibit, 1999, Reno, United States, 1/11/99.
Anderson BA, Wygnanski IJ, Gutmark EJ. Noise reduction by interaction of flexible filaments with an underexpanded supersonic jet. In 37th Aerospace Sciences Meeting and Exhibit. American Institute of Aeronautics and Astronautics Inc, AIAA. 1999. AIAA 99-0080
Anderson, Bruce A. ; Wygnanski, Israel J ; Gutmark, Ephraim J. / Noise reduction by interaction of flexible filaments with an underexpanded supersonic jet. 37th Aerospace Sciences Meeting and Exhibit. American Institute of Aeronautics and Astronautics Inc, AIAA, 1999.
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