The separation of radiating and non-radiating near-field pressure fluctuations in supersonic jets

Du, Yongle; Morris, Philip J.

doi:10.1016/j.jsv.2015.06.020

Cited by 16 publications

(6 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The steady laminar solutions are obtained with an in-house code named “CHOPA”, and the main features are summarized by Du and Morris. 29,45 The rectangular computational domain measures 300 × 100. The computational grids are uniformly distributed in the streamwise direction with grid spacings Δ x = 1, but are locally refined in the lateral direction inside the mixing layer with grid spacings Δ y = 0.05, and gradually stretched in the lateral direction until Δ y = 1.75 when the upper and lower boundaries are reached.…”

Section: Case Descriptionmentioning

confidence: 99%

Hydrodynamic sources of the vortex sound in a two-dimensional shear layer

Liu

et al. 2023

International Journal of Aeroacoustics

Self Cite

View full text Add to dashboard Cite

Development of advanced noise reduction devices requires an in-depth understanding of two fundamental questions: what are the true noise sources and how are the acoustic radiations generated. An accurate separation of the hydrodynamic and acoustic fluctuations helps to reveal the answers, but no consensus exists on its feasibility in the near-field source region of compressible flows. This study proposes a methodology to examine the dynamics of vortex sound generation in a two-dimensional artificially excited subsonic mixing layer. The parabolized stability equation (PSE) is applied to resolve the hydrodynamic fluctuations and the vortex sound theory is used to predict the acoustic pressures. Numerical simulations show that the PSE solutions capture the vortex pairing reasonably accurately and damp the acoustic modes to a negligible level, and that the vortex sound theory recovers the acoustic pressures. Good agreement of both solutions with the direct simulations indicates that a physically reasonable separation of hydrodynamic sources is achieved and can be used to further examine the vortex dynamics and noise source mechanisms.

show abstract

Section: Case Descriptionmentioning

confidence: 99%

Hydrodynamic sources of the vortex sound in a two-dimensional shear layer

Liu

et al. 2023

International Journal of Aeroacoustics

Self Cite

View full text Add to dashboard Cite

show abstract

“…7), multiple values of z i were sometimes discovered to meet the criteria of Eq. (14). In such cases, the selection of z i closest to z 0 was enforced.…”

Section: B Analytical Wavepacket Modelingmentioning

confidence: 99%

“…For example, decomposition methods that result in loworder models (the inclusion of the dominant energy in one or very few terms) are commonly used to obtain PFs for the turbulent flow, 6,7 for the radiated acoustic field, 8,9 to investigate correlations between flow and radiation, 1,10-12 and to serve as wavepacket models for sound field predictions. 4,10,[13][14][15] These methods, motivated by efficiency, typically employ a singular value decomposition (SVD) of the cross-spectral matrix of flow or acoustic field information. An advantage of these methods is that equivalent source characteristics related to the most dominant field energies can be extracted.…”

Section: Introductionmentioning

confidence: 99%

Partial-field decomposition analysis of full-scale supersonic jet noise using optimized-location virtual references

Wall

Gee

Leete

et al. 2018

The Journal of the Acoustical Society of America

View full text Add to dashboard Cite

Supersonic jet noise reduction efforts benefit from targeted source feature extraction and high-resolution acoustic imaging. Another useful tool for feature extraction is partial field decomposition of sources into independent contributors. Since such decomposition processes are nonunique, care must be taken in the physical interpretation of decomposed partially coherent aeroacoustic fields. The optimized-location virtual reference method (OLVR) is a partial field decomposition designed to extract physically meaningful source and field information through the strategic placement of virtual references within a reconstructed field. The OLVR method is applied here to obtain spatially distinct and ordered partial sources at multiple frequencies of a full-scale, high-performance supersonic jet engine operating at 100% engine power. Partial sources are shown to mimic behaviors of the total source distributions including monotonic growth and decay. Because of finite spatial coherence, multiple partial sources are used to reproduce far-field radiation away from the main lobe, and the number of required sources increases with increasing frequency. An analytical multiwavepacket model is fitted to the partial sources to demonstrate how OLVR partial fields can be leveraged to produce reduced-order models.

show abstract

“…Techniques to separate the convecting from radiating pressure fluctuations based on phase speeds of pressure fluctuations, using methods such as reduced-order models or spectral techniques, may be found Refs. [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

A Time-Domain Linear Method for Jet Noise Prediction and Control Trend Analysis

Prasad,

Gaitonde

2021

Preprint

View full text Add to dashboard Cite

Large-scale turbulent structures in the form of coherent wavepackets play a significant role in the generation of prominent shallow-angle noise radiation of jets. Economical prediction tools often model these wavepackets in the frequency-domain using stability modes of the mean flow. The use of simplifying choices, such as parabolized equations and azimuthal decomposition, provide efficient methods but can impose constraints on rate of streamwise variation of the mean state or geometric complexity. The current investigation develops a time-domain linearized Navier-Stokes-based approach predicated on the mean basic state for two goals: (i) to obtain the radiated shallow-angle noise field, including that from imperfectly expanded jets containing shock trains, and (ii) to estimate noise control trends with actuator frequency. A previously developed implicit linearization technique repurposing native non-linear Navier-Stokes code capabilities avoids any additional constraints on nozzle geometry, while its time-domain nature facilitates control analysis through transient pulse response. Two other integral components of the method are the sifting of linearized perturbations to isolate the acoustic component according to Doak's momentum potential theory (MPT), and subsequently Dynamic Mode Decomposition (DMD) to analyze the response in different spectral ranges. Comparisons with well-validated Large Eddy Simulation (LES) databases in different spectral ranges show accurate model predictions for super-radiative shallow angle noise, including for hot jets from military-style nozzles. For control frequency effectiveness, the transient perturbation growth characteristics are processed to delineate the distinct effects of the excitation on vorticity versus the MPT acoustic variable. For a specific jet with extensive published experimental data using plasma actuators, it is shown that the method correctly predicts noise amplification at lower frequencies and reduction at higher values, at the observed crossover location.Considerations on the costs associated with the approach, which exploits linearity to extract results at multiple frequencies with each simulation, are outlined.

show abstract

The separation of radiating and non-radiating near-field pressure fluctuations in supersonic jets

Cited by 16 publications

References 37 publications

Hydrodynamic sources of the vortex sound in a two-dimensional shear layer

Hydrodynamic sources of the vortex sound in a two-dimensional shear layer

Partial-field decomposition analysis of full-scale supersonic jet noise using optimized-location virtual references

A Time-Domain Linear Method for Jet Noise Prediction and Control Trend Analysis

Contact Info

Product

Resources

About