High Subsonic Jet Experiments: Turbulence and Noise Generation Studies

Narayanan, S.; Barber, Thomas J.; Polak, David R.

doi:10.2514/2.1692

Cited by 83 publications

(38 citation statements)

References 12 publications

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“…Broadly speaking, as the Strouhal number increases from 0.1 to 10, the location of the peak noise moves upstream from x/D ≈ 7 to x/D = 0. This trend is similar to that found in cold subsonic jets by Narayanan et al 5 and by Lee and Bridges. 6 Near Sr = 0.3 both source location plots do a small "zig-zag" that is also noticeable in some of the noise source location plots of Lee and Bridges.…”

Section: Direct Resultssupporting

confidence: 79%

“…3 The theoretical foundation of noise source location using cross-correlations of multiple microphone signals was established by Billingsley and Kinns. More recently, frequency-domain approaches for processing the microphone array data were introduced by Humphreys et al 4 Narayanan et al 5 conducted a combined experimental study of the flow characteristics and noise source distribution, using a phased array, of cold and hot subsonic jets. One of the important findings is that the peak noise source is located near the end of the potential core.…”

Section: Introductionmentioning

confidence: 99%

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Localization of Multiple Types of Jet Noise Sources

Papamoschou

Dadvar

2006

12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference)

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A small-aperture microphone phased array provides noise source maps for turbulent mixing noise emitted from a cold Mach 0.9 jet in two polar directions. The first direction is at 30 degrees to the jet axis and is associated with noise produced by large-scale turbulence. The second direction is at 90 degrees to the jet axis and is associated with noise generated from fine-scale turbulence. The measurements show similarities and differences between the two noise source maps. At given frequency, the axial distributions of large-scale and fine-scale noise sources have comparable shapes. Both types of noise sources peak near the end of the potential core and move towards the nozzle exit as frequency increases. Along the path of peak noise on the space-frequency diagram, the spectra of the two noise sources are distinct and representative of their respective similarity spectra for single point measurement.

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Section: Direct Resultssupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Localization of Multiple Types of Jet Noise Sources

Papamoschou

Dadvar

2006

12th AIAA/CEAS Aeroacoustics Conference (27th AIAA Aeroacoustics Conference)

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“…5 This entails imaging of the noise source with a narrow-aperture array so that the two types of noise sources are not mixed up on a given array measurement. Although a significant number of studies have used microphone arrays to image jet noise, 1,[6][7][8] the array apertures were too large to distinguish between the two types of noise sources. Further, the effects of directivity were not addressed in a consistent manner.…”

Section: Introductionmentioning

confidence: 99%

Imaging of Directional Distributed Noise Sources

Papamoschou

2008

14th AIAA/CEAS Aeroacoustics Conference (29th AIAA Aeroacoustics Conference)

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This study relates to the imaging of noise sources that are distributed and strongly directional, such as in turbulent jets. The goal is to generate noise source maps that are self-consistent, i.e., their integration over the extent of the noise source region gives the far-field pressure autospectrum for a particular emission direction. This is possible by including a directivity factor in the formulation of the source cross-spectral density. The resulting source distribution is based on the complex coherence, rather than the cross-spectrum, of the measured acoustic field. For jet noise, which is not only directional but whose nature changes with emission angle, it is necessary to conduct the measurements with a narrow-aperture array. The resulting images must be devoid to the extent possible of spatial distortions caused by the array response. Two methods for obtaining clean images are addressed: deconvolution of the beamformer output and direct spectral estimation. The two techniques produced similar noise source maps for a Mach 0.9 cold jet.

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“…In the numerical simulations, since it was deemed computationally too expensive to include the nozzle geometry, laminar shear layers were fed into the domain and randomized velocity fluctuations in the form of a vortex ring were imposed into the jet shear layers. Moreover, it has been observed experimentally 61,62 that high-frequency sources are located a small distance downstream of the jet nozzle and a significant portion of the noise spectrum originates from this near field of the jet. Hence, the high-frequency noise generated in the near-nozzle jet shear layer within a few diameters downstream of the nozzle exit is missing in the current simulations.…”

mentioning

confidence: 99%

Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction

Uzun

Lyrintzis

Blaisdell

2004

42nd AIAA Aerospace Sciences Meeting and Exhibit

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This study is focused on developing a Computational Aeroacoustics (CAA) methodology that couples the near field unsteady flow field data computed by a 3-D Large Eddy Simulation (LES) code with various integral acoustic formulations for the far field noise prediction of turbulent jets. Noise computations performed for a Reynolds number 400,000 jet using various integral acoustic results are presented and the results are compared against each other as well with an experimental jet at similar flow conditions. Our results show that the surface integral acoustics methods (Kirchhoff and Ffowcs Williams -Hawkings) give similar results to the volume integral method (Lighthill's acoustic analogy) at a much lower cost. To our best knowledge, Lighthill's acoustic analogy was applied to a reasonably high Reynolds number jet for the first time in this study. A database greater than 1 Terabytes (TB) in size was post-processed using 1160 processors in parallel on a modern supercomputing platform for this purpose.

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High Subsonic Jet Experiments: Turbulence and Noise Generation Studies

Cited by 83 publications

References 12 publications

Localization of Multiple Types of Jet Noise Sources

Localization of Multiple Types of Jet Noise Sources

Imaging of Directional Distributed Noise Sources

Coupling of Integral Acoustics Methods with LES for Jet Noise Prediction

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