Vector Aeroacoustics for a Uniform Mean Flow: Acoustic Intensity and Acoustic Power

Xu, Chunxiao; Mao, Yijun; Hu, Zhiwei; Ghorbaniasl, Ghader

doi:10.2514/1.j056853

Cited by 3 publications

(4 citation statements)

References 21 publications

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“…By employing the developed acoustic velocity formulations, we analyze the effect of the Mach number of uniform mean flow on the acoustic intensity field and acoustic power output in the next paper [52]. Moreover, the acoustic and vortical disturbances scattered by solid boundaries in uniform mean flow could be studied, and detailed investigations on this topic are planned in future research.…”

Section: Discussionmentioning

confidence: 99%

Vector Aeroacoustics for Uniform Mean Flow: Acoustic Velocity and Vortical Velocity

Mao

et al. 2018

AIAA Journal

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Section: Discussionmentioning

confidence: 99%

Vector Aeroacoustics for Uniform Mean Flow: Acoustic Velocity and Vortical Velocity

Mao

et al. 2018

AIAA Journal

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“…Following the research idea of the FW-H equation, the objective of this section is to derive a generalized form of the 4D wave equation (23) in the presence of a permeable surface with moving velocity. It is assumed that the unit normal vector at the permeable surface directs from the boundary to the flow field.…”

Section: The 4d Fw-h Equation For the Uniformly Moving Flowmentioning

confidence: 99%

“…ω denotes the vibrating angular frequency of the point source, and the wavenumber is calculated with k=ω/c∞.The acoustic velocity, pressure and density are given as: As a validation example，the selection of wave number and Mach number does not impact the numerical predictions, as long as they align with the physical background. Based on research work in literatures [19,21,23], the wavenumber is chosen as k=2, and the time evolution of the acoustic vector signal at θ=120̊ for the incoming flow with M∞=0.6 is shown in Figure 2. It is demonstrated that the numerical results of the acoustic pressure and acoustic velocities are in good agreement with the analytical solutions, and they are approximately presented as single-period cosine waves.…”

Section: The Stationary Monopole Source and Dipole Source In The Unif...mentioning

confidence: 99%

“…The wavenumber is chosen as k=2, Figure 6 shows the sound pressure level (SPL) and the sound velocity level (SVL) of rotating monopole source with distance at different Mach numbers. The SPL and SVL were calculated with the following formulas [23]: Figure 6 demonstrates that the amplitude of SPL and SVL decays rapidly with distance. The higher the Mach number, the faster the amplitude of SPL and SVL increases at a given distance.…”

Section: The Rotating Monopole Source In the Uniformly Moving Mediummentioning

confidence: 99%

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An Investigation into the Four-Dimensional Acoustic Analogy Model for Homogeneous Media and the Prediction of Flow-Induced Noise in Spatio-Temporal Fields

Zheng,

Cai,

Wang

2024

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In practical engineering, the prevalence of uniform flow-induced noise poses significant challenges. Traditional models, notably Lighthill's acoustic analogy, have primarily focused on the acoustic pressure distribution, neglecting the integral role of acoustic velocity. This study introduces a novel four-dimensional (4D) acoustic wave equation model derived from the Navier-Stokes equations for fluid mechanics. This model uniquely incorporates acoustic pressure alongside three directional acoustic velocities as fundamental acoustic variables, offering a comprehensive framework for noise prediction. By integrating these variables, a 4D Ffowcs Williams-Hawkings (FW-H) equation is formulated, encapsulating the complexities of an arbitrary smooth permeable surface surrounding the noise-generating structure. Furthermore, this research innovates by establishing a time-domain integral formula for the 4D FW-H equation, incorporating a time-domain Green's function that accounts for the influence of uniform flow. Through numerical simulations involving stationary and rotating point sources within a uniformly moving medium, the efficacy of the proposed method is demonstrated. The method exhibits exceptional accuracy in capturing far-field 4D acoustic signals, aligned with analytical solutions, and reveals the characteristic Doppler effect in the acoustic fields of rotating monopole and dipole sources. A detailed investigation into the noise distribution within spatio-temporal fields under varying incident velocities, wave numbers, and propagation distances is conducted. Findings indicate a pronounced convective effect on the acoustic vector signal within a moving medium, with near-field 4D acoustic variables exhibiting nonlinear relationships with incoming flow velocity, wave number, and propagation distance, whereas far-field variables adhere to linear propagation patterns. This study diverges from conventional methodologies by considering the uniform flow's impact and devising an acoustic model capable of swiftly and accurately determining sound pressure and acoustic velocity. The developed acoustic calculation model offers valuable reference data for noise reduction and engineering structure optimization.

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Temporal and spatial characteristics of monopole acoustic energy dominated by unsteady thermodynamic cavitating flow

et al. 2021

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Vector Aeroacoustics for a Uniform Mean Flow: Acoustic Intensity and Acoustic Power

Cited by 3 publications

References 21 publications

Vector Aeroacoustics for Uniform Mean Flow: Acoustic Velocity and Vortical Velocity

Vector Aeroacoustics for Uniform Mean Flow: Acoustic Velocity and Vortical Velocity

An Investigation into the Four-Dimensional Acoustic Analogy Model for Homogeneous Media and the Prediction of Flow-Induced Noise in Spatio-Temporal Fields

Temporal and spatial characteristics of monopole acoustic energy dominated by unsteady thermodynamic cavitating flow

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