On the two components of turbulent mixing noise from supersonic jets

Tam, Christopher K. W.; Golebiowski, Michel; Seiner, J. M.

doi:10.2514/6.1996-1716

Cited by 356 publications

(374 citation statements)

References 25 publications

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“…These two radiations have similar characteristics of directivity, frequency and spectral shape to that of a jet issuing from a conventional nozzle. Indeed the mixing noise is in agreement with the dual source model of Tam 4,18 and the screech frequency evolves according to the models elaborated for axisymmetric nozzles.…”

Section: Discussionsupporting

confidence: 60%

“…This observation validates once again the presence of the double acoustic source in the mixing noise of the diaphragms. Based on this modeling of the jet mixing noise, Tam et al 18 have empirically elaborated the acoustic spectra associated with the radiation of large coherent turbulent structures (typical of downstream radiation at 30 • ) called Glog and the one associated with the radiation of small scale turbulence (typical of sideline radiation 90 • ) termed Flog. These spectra were obtained using a large jet noise data bank.…”

Section: A Study Of the Mixing 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: Discussionsupporting

confidence: 60%

Section: A Study Of the Mixing Noisementioning

confidence: 99%

Experimental investigation of the transient bleed valve noise

Laffay

Jacob

Moreau

et al. 2017

23rd AIAA/CEAS Aeroacoustics Conference

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“…(c) Data-driven modelling and uncertainty quantification For jet noise, experimental evidence suggests that supersonic turbulent mixing noise may be composed of two different components, corresponding to the large and small scales of turbulent motion [155,156]. Advanced data-decomposition methods applied to experimental farfield acoustic measurements from high-speed jets failed, however, to separate the data into two different statistically independent components for all radiation angles [157].…”

Section: (A) Trends In Hpc: Towards Exascale Computingmentioning

confidence: 99%

A second golden age of aeroacoustics?

Lele

Nichols

2014

Phil. Trans. R. Soc. A.

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In 1992, Sir James Lighthill foresaw the dawn of a second golden age in aeroacoustics enabled by computer simulations (Hardin JC, Hussaini MY (eds) 1993 Computational aeroacoustics, New York, NY: Springer (doi:10.1007). This review traces the progress in large-scale computations to resolve the noise-source processes and the methods devised to predict the far-field radiated sound using this information. Keeping focus on aviation-related noise sources a brief account of the progress in simulations of jet noise, fan noise and airframe noise is given highlighting the key technical issues and challenges. The complex geometry of nozzle elements and airframe components as well as the high Reynolds number of target applications require careful assessment of the discretization algorithms on unstructured grids and modelling compromises. High-fidelity simulations with 200-500 million points are not uncommon today and are used to improve scientific understanding of the noise generation process in specific situations. We attempt to discern where the future might take us, especially if exascale computing becomes a reality in 10 years. A pressing question in this context concerns the role of modelling in the coming era. While the sheer scale of the data generated by large-scale simulations will require new methods for data analysis and data visualization, it is our view that suitable theoretical formulations and reduced models will be even more important in future.

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“…Additionally, a gamma distribution was chosen over a simple Gaussian as it encompasses the non-symmetric broadband spectral peak [37]. Finally, the large scale structure peak was determined by curve-fitting the large scale similarity spectrum of Tam et al [38] to the acoustic data acquired at an observation angle of 150°for Strouhal numbers less than 1. Due to the presence of broadband shock associated noise in the higher frequency range, extraction of the small scale turbulence noise through use of the fine scale structure similarity spectrum was not possible using the current data set.…”

Section: Acoustic Fieldmentioning

confidence: 99%