Modal Analysis of a Subsonic Hot Jet LES with Comparison to the Linear Stability Analysis

Muller, Frederic; Vincent, François; Rahier, Gilles; Casalis, Grégoire

doi:10.2514/6.2005-2886

Cited by 10 publications

(3 citation statements)

References 9 publications

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“…To quantify the amplification of the instability waves between the nozzle and the plate, the growth rates of the Kelvin-Helmholtz waves are integrated between z = 0 and L, as done in previous works, 30,33,[59][60][61][62] giving the power gain A:…”

Section: Shear-layer Velocity Spectramentioning

confidence: 99%

Acoustic tones generated by impinging jets: Differences between laminar and highly-disturbed nozzle-exit boundary layers

Varé,

Bogey

2024

International Journal of Aeroacoustics

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The differences between the acoustic tones generated by impinging jets with laminar and highly-disturbed nozzle-exit boundary layers are investigated. For that, jets at Mach numbers between 0.6 and 1.3 impinging on a flat plate at a distance of 8 nozzle radii from the nozzle exit are computed using large-eddy simulations. The amplitudes of the tones generated by the jets through feedback loops establishing between the nozzle and the plate are found to be significantly affected by the exit turbulent disturbances. In the present study, overall, they are lower for the initially laminar jets than for the initially disturbed ones. The level decrease varies from a few dB up to 15 dB, depending on the tones, which can change the frequencies of the dominant tones and the numbers and azimuthal structures of their associated feedback modes. For Mach numbers 0.75 and 0.8, for instance, the dominant tone frequencies are approximately two times lower for the initially laminar jets than for the other ones, yielding a better agreement with experiments of the literature in the former case. For a Mach number of 1.1, as a second example, the dominant tone is associated with the axisymmetric third feedback mode in the laminar case but with the helical fifth feedback mode in the disturbed case. The differences in the tone amplitude are finally discussed by estimating the power gains of the shear-layer instability waves between the nozzle and the plate using linear stability analysis for the axisymmetric mode. In most cases, at the frequency of a specific tone, the higher the gain, the stronger the acoustic tone.

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Section: Shear-layer Velocity Spectramentioning

confidence: 99%

Acoustic tones generated by impinging jets: Differences between laminar and highly-disturbed nozzle-exit boundary layers

Varé,

Bogey

2024

International Journal of Aeroacoustics

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“…At the location r/D=5, there is a good agreement between the experimental data and the simulation. Hall et al [31], Coiffet [32] and Muller [18] among other authors studied the azimuthal structure of near field pressure and observed that low wave number modes are dominant and the axisymmetric one (m=0) has a downstream growing contribution. The modes |m| < 5 include the most part of energy in the near field.…”

Section: Near Field Pressurementioning

confidence: 99%

“…These spectra are plotted for the range [0. [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Section: Far Field Pressurementioning

confidence: 99%

Large-Eddy Simulation and Far Field Acoustics of a Subsonic Hot Jet

Labbé¹

2016

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016)

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Analysis of noise radiation mechanisms in hot subsonic jet from a validated large eddy simulation solution

2015

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In the framework of jet noise computation, a numerical simulation of a subsonic turbulent hot jet is performed using large-eddy simulation. A geometrical tripping is used in order to trigger the turbulence at the nozzle exit. In a first part, the validity of the simulation is assessed by comparison with experimental measurements. The mean and rms velocity fields show good agreement, so do the azimuthal composition of the near pressure field and the far field spectra. Discrepancies remain close to the nozzle exit which lead to a limited overestimation of the pressure levels in both near and far fields, especially near the 90∘ angular sector. Two point correlation analyses are then applied to the data obtained from the simulation. These enable to link the downstream acoustic radiation, which is the main direction of radiation, to pressure waves developing in the shear layer and propagating toward the potential core end. The intermittency of the downstream acoustic radiation is evidenced and related to the coherent structures developing in the shear layer.

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Modal Analysis of a Subsonic Hot Jet LES with Comparison to the Linear Stability Analysis

Cited by 10 publications

References 9 publications

Acoustic tones generated by impinging jets: Differences between laminar and highly-disturbed nozzle-exit boundary layers

Acoustic tones generated by impinging jets: Differences between laminar and highly-disturbed nozzle-exit boundary layers

Large-Eddy Simulation and Far Field Acoustics of a Subsonic Hot Jet

Analysis of noise radiation mechanisms in hot subsonic jet from a validated large eddy simulation solution

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