Supersonic Jet Noise

Tam, Christopher K. W.

doi:10.1146/annurev.fl.27.010195.000313

Cited by 781 publications

(331 citation statements)

References 30 publications

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“…Acoustic waves are thus created which, in particular, go back to the nozzle and excite the shear layer, creating new vortices and thus closing the loop. [6][7][8][9][10] The broadband contribution is also produced by the interaction of vortices with the shock cells but without feedback loop. [11][12][13] Although acoustically interesting and used in a large number of industrial sectors for discharging flow or generating pressure drops, acoustic radiation from a flow through a perforated plate or more generally from multiple jet nozzle has been very little studied in the literature.…”

Section: Figure 1 Experimental Setup and Of Few Typical Samplesmentioning

confidence: 99%

“…Due to its strong acoustic signature, screech has been thorougly studied since the first work of Powell in 1954. [6][7][8][9][10]13 Although it is not yet fully understood, the various works agree to say that the general aeroacoustic mechanism responsible for this tonal noise is a feedback loop: vortices are generated and convected by the shear layer through the shock cells and interact with them. Acoustic waves are thus created which, in particular, go back to the nozzle and excite the shear layer, creating new vortices and thus closing the loop.…”

Section: B Study Of the Shock-associated Noisementioning

confidence: 99%

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Experimental investigation of the transient bleed valve noise

Laffay

Jacob

Moreau

et al. 2017

23rd AIAA/CEAS Aeroacoustics Conference

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This study presents the first step of an experimental study of the transient bleed valve noise. It was carried out on a simplified TBV geometry composed of a cylindrical inlet pipe leading to a diaphragm or a perforated disk for the purpose of generating pressure drops. Numerous diaphragms and grids have been tested in order to identify parameters that influence the acoustic radiation of the TBV and for NPR (Nozzle pressure ratio) from 1.2 to 3.6 to cover both subsonic and supersonic regimes. A large number of acoustic behaviors have been identified. For diaphragms far field acoustic spectra is dominated by mixing noise for all NPR and by shock-associated noise (screech and broadband shock associated noise (BBSAN)) when the critical value of the NPR delimiting the subsonic and supersonic behavior (NPRc = 1.89) is exceeded. For grids the mixing noise is still present but is composed of two humps. The parametric study allowed to associate the first hump to the noise of an equivalent jet having the smallest diameter encircling the grid perforations while the second is associated to the noise of the outer isolated jets. A first prediction model has thus been proposed based on this double source. Furthermore, the grids offer a significant noise reduction in the audible range with respect to a diaphragm of the same cross-section by shifting the radiation towards the high frequencies. The noise associated with supersonic phenomena (screech and BBSAN) are also strongly reduced and even suppressed in most of the tested cases.

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Section: Figure 1 Experimental Setup and Of Few Typical Samplesmentioning

confidence: 99%

Section: B Study Of the Shock-associated Noisementioning

confidence: 99%

Experimental investigation of the transient bleed valve noise

Laffay

Jacob

Moreau

et al. 2017

23rd AIAA/CEAS Aeroacoustics Conference

View full text Add to dashboard Cite

show abstract

“…Mechanisms of noise generation are relatively less well understood for subsonic jets than for supersonic jets [1] where turbulence-driven linear instability modes of the jet column act as important sound sources. In subsonic jets the radiation efficiency of such modes is low and it appears likely that non-linear interactions play a role, either as interactions between primary instability waves or (as in the original Lighthill [2] analysis) as interactions between fully-turbulent velocity components.…”

Section: Introductionmentioning

confidence: 99%

Sound radiation from exponentially growing and decaying surface waves

Sandham

Morfey

2006

Journal of Sound and Vibration

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A simplified model problem is used to illustrate some of the parameters controlling the radiation of sound into an ambient medium due to the growth and subsequent decay of subsonic travelling waves, such as may occur via non-linear interactions in turbulent free shear flows. It is shown that substantial sound may be generated by apparently subsonic modes as a result of their growth and decay characteristics. Low frequency modes that saturate over a short timescale are the most effective radiators. r

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“…There has been ample evidence that instability waves are major sources of noise in supersonic jets. [1][2][3][4][5][6] The noise generation is most efficient when the phase speed of an instability wave is supersonic relative to the ambient fluid and intense Mach waves are emitted. [7][8][9] Therefore, determination of stability characteristics of supersonic jets is a vital step for the prediction of jet noise, where compressibility often plays an important role.…”

Section: Introductionmentioning

confidence: 99%

Instability of vortical and acoustic modes in supersonic round jets

Luo

Sandham

1997

Physics of Fluids

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The stability of ''top-hat'' and fully developed jet profiles is investigated by an inviscid linear stability theory for compressible flow. The study covers a wide range of the Mach number and the temperature ratio. Two types of instabilities are found: vortical and acoustic, each of which can be subdivided into non-radiating ͑subsonic͒ and radiating ͑supersonic͒ modes. The vortical mode is the continuation of the Kelvin-Helmholtz instability from incompressible flow. The acoustic mode is a compressible flow phenomenon, which becomes important at large Mach numbers. Temperature-ratio effects can be destabilizing or stabilizing, depending on the Mach number and mode of instability. A spectrum of unstable acoustic modes, including axisymmetric ones, are found to exist in the fully developed jet. For this jet, acoustic axisymmetric waves become more unstable than both vortical and acoustic helical waves at Mach numbers over about 3. Strong evidence of a resonance mechanism for acoustic modes is seen in the growth rate curves at high Mach numbers, where a spectrum of local peaks and valleys appears at regularly distributed frequencies. © 1997 American Institute of Physics.

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Supersonic Jet Noise

Cited by 781 publications

References 30 publications

Experimental investigation of the transient bleed valve noise

Experimental investigation of the transient bleed valve noise

Sound radiation from exponentially growing and decaying surface waves

Instability of vortical and acoustic modes in supersonic round jets

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