Effect of fluid injection on turbulence and noise reduction of a supersonic jet

Chitrarth Prasad, Philip Morris

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Supersonic jets, such as the ones used in high-performance military aircraft, have both downstream and upstream noise components due to the large-scale turbulent structures and the presence of shock cells in the jet plume. The fluid insert technology is a noise reduction method that has been shown to effectively reduce both these noise components. This paper analyses the unsteady flow changes associated with different fluid insert configurations with a goal of helping to understand the detailed noise reduction mechanisms. Using direct cross-correlations of the near-field data with the far-field microphone signals, it is found that even the use of a single injector as a fluid insert helps break up the large-scale structures of the flow. However, a more azimuthally distributed blowing is required to reduce the upstream broadband shock-Associated noise (BBSAN). Addition of upstream injectors at each azimuthal location further enhances the BBSAN reduction. Decomposition of the jet flow-field into hydrodynamic and acoustic modes shows that fluid insert nozzles reduce the amplitude and convection speed of the coherent acoustic mode in the plane of highest noise reduction. This article is part of the theme issue 'Frontiers of aeroacoustics research: Theory, computation and experiment.

Original languageEnglish (US)
Article number20190082
JournalPhilosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences
Volume377
Issue number2159
DOIs
StatePublished - Dec 2 2019

Fingerprint

fluid injection
Die casting inserts
Noise Reduction
Noise abatement
noise reduction
Turbulence
Injection
inserts
turbulence
upstream
Fluid
Shock
Injector
Fluids
fluids
shock
injectors
nozzle inserts
Broadband
Acoustics

All Science Journal Classification (ASJC) codes

  • Mathematics(all)
  • Engineering(all)
  • Physics and Astronomy(all)

Cite this

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title = "Effect of fluid injection on turbulence and noise reduction of a supersonic jet",
abstract = "Supersonic jets, such as the ones used in high-performance military aircraft, have both downstream and upstream noise components due to the large-scale turbulent structures and the presence of shock cells in the jet plume. The fluid insert technology is a noise reduction method that has been shown to effectively reduce both these noise components. This paper analyses the unsteady flow changes associated with different fluid insert configurations with a goal of helping to understand the detailed noise reduction mechanisms. Using direct cross-correlations of the near-field data with the far-field microphone signals, it is found that even the use of a single injector as a fluid insert helps break up the large-scale structures of the flow. However, a more azimuthally distributed blowing is required to reduce the upstream broadband shock-Associated noise (BBSAN). Addition of upstream injectors at each azimuthal location further enhances the BBSAN reduction. Decomposition of the jet flow-field into hydrodynamic and acoustic modes shows that fluid insert nozzles reduce the amplitude and convection speed of the coherent acoustic mode in the plane of highest noise reduction. This article is part of the theme issue 'Frontiers of aeroacoustics research: Theory, computation and experiment.",
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N2 - Supersonic jets, such as the ones used in high-performance military aircraft, have both downstream and upstream noise components due to the large-scale turbulent structures and the presence of shock cells in the jet plume. The fluid insert technology is a noise reduction method that has been shown to effectively reduce both these noise components. This paper analyses the unsteady flow changes associated with different fluid insert configurations with a goal of helping to understand the detailed noise reduction mechanisms. Using direct cross-correlations of the near-field data with the far-field microphone signals, it is found that even the use of a single injector as a fluid insert helps break up the large-scale structures of the flow. However, a more azimuthally distributed blowing is required to reduce the upstream broadband shock-Associated noise (BBSAN). Addition of upstream injectors at each azimuthal location further enhances the BBSAN reduction. Decomposition of the jet flow-field into hydrodynamic and acoustic modes shows that fluid insert nozzles reduce the amplitude and convection speed of the coherent acoustic mode in the plane of highest noise reduction. This article is part of the theme issue 'Frontiers of aeroacoustics research: Theory, computation and experiment.

AB - Supersonic jets, such as the ones used in high-performance military aircraft, have both downstream and upstream noise components due to the large-scale turbulent structures and the presence of shock cells in the jet plume. The fluid insert technology is a noise reduction method that has been shown to effectively reduce both these noise components. This paper analyses the unsteady flow changes associated with different fluid insert configurations with a goal of helping to understand the detailed noise reduction mechanisms. Using direct cross-correlations of the near-field data with the far-field microphone signals, it is found that even the use of a single injector as a fluid insert helps break up the large-scale structures of the flow. However, a more azimuthally distributed blowing is required to reduce the upstream broadband shock-Associated noise (BBSAN). Addition of upstream injectors at each azimuthal location further enhances the BBSAN reduction. Decomposition of the jet flow-field into hydrodynamic and acoustic modes shows that fluid insert nozzles reduce the amplitude and convection speed of the coherent acoustic mode in the plane of highest noise reduction. This article is part of the theme issue 'Frontiers of aeroacoustics research: Theory, computation and experiment.

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