Aeroacoustics research in Europe: The CEAS-ASC report on 2019 highlights

Camussi, Roberto; Bennett, Gareth J.

doi:10.1016/j.jsv.2020.115540

Cited by 22 publications

(12 citation statements)

References 64 publications

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“…The classical motivation for aircraft noise characterization stems from human factors considerations for both the occupant of the aircraft, and the emitted environmental noise. Noise reduction strategies are fueled by increasingly stringent regulations [21], and the recent research within the European aeroacoustic community has been summarized by Camussi and Bennett [42]. The characterization of aircraft noise with the specific objective of passive acoustic-based tracking is a niche contribution but aims to bridge the knowledge silos.…”

Section: Aircraft Noise Sources For Trackingmentioning

confidence: 99%

Recent Advances in Passive Acoustic Localization Methods via Aircraft and Wake Vortex Aeroacoustics

Joshi

Rahman

Hickey

2022

Fluids

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Passive acoustic aircraft and wake localization methods rely on the noise emission from aircraft and their wakes for detection, tracking, and characterization. This paper takes a holistic approach to passive acoustic methods and first presents a systematic bibliographic review of aeroacoustic noise of aircraft and drones, followed by a summary of sound generation of wing tip vortices. The propagation of the sound through the atmosphere is then summarized. Passive acoustic localization techniques utilize an array of microphones along with the known character of the aeroacoustic noise source to determine the characteristics of the aircraft or its wake. This paper summarizes the current state of knowledge of acoustic localization with an emphasis on beamforming and machine learning techniques. This review brings together the fields of aeroacoustics and acoustic-based detection the advance the passive acoustic localization techniques in aerospace.

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Section: Aircraft Noise Sources For Trackingmentioning

confidence: 99%

Recent Advances in Passive Acoustic Localization Methods via Aircraft and Wake Vortex Aeroacoustics

Joshi

Rahman

Hickey

2022

Fluids

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“…With increasingly stringent noise regulations worldwide, mitigation of the aerodynamic noise from other airframe parts, such as high-lifting wings and landing gears, has received increasing research efforts, since the engine noise has reached to the similar levels of these airframe parts especially during landing. 1,2 Apparently, an in-depth understanding of the dynamics of the noise generation process is indispensable in order to develop more sophisticated noise reduction concepts. However, it remains as a scientific challenge even for simple sheared flows.…”

Section: Introductionmentioning

confidence: 99%

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

Liu

et al. 2023

International Journal of Aeroacoustics

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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.

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“…The range of Reynolds numbers from 300 to 1.3 × 10 5 , where the flow remains laminar in the boundary layer and turbulent instabilities begin in the separated shear layers, is known as the subcritical regime. 9,10 The recent research works 11,12 focus on noise mitigation methods for quieter applications; hence the flow and acoustic studies on fundamental problems provide a better understanding.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic noise characteristics of non-circular cylinders in subcritical flow regime

Jothi

2022

International Journal of Aeroacoustics

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The present study experimentally investigates the aerodynamic noise from the flow around cylinders of square and equilateral triangle cross-sections at different angles of incidence ( α). The cylinder models have a side dimension of 10 mm and a span of 300 mm. The free stream velocity ( U 0) is in the range of 12–36 m/s, and the corresponding Reynolds numbers are 7.8 × 103 to 2.3 × 104, which is in the subcritical flow regime. The characteristic acoustic tones are generated at α = 30° and 45° for square and triangular cylinders. The frequency of acoustic tones linearly increases with the free stream velocity, and the corresponding Strouhal numbers are found to be in the range of 0.13–0.16. Depending on the angle of incidence, the overall sound pressure level is higher than the background noise by 4–24 dB for the square cylinder and 3–15 dB for the triangular cylinder at U 0 = 36 m/s. The highest noise level of the square cylinder is 90 dB at α = 45° and 79 dB at α = 30° for the triangular cylinder. The spectral scaling with the sixth power of the free stream velocity indicates the dipole behaviour of the acoustic tones. The mean and root-mean-square velocity profiles in the wake region characterise the noise emissions at different angles of incidence. The comparative acoustic study of the non-circular cylinders with a circular counterpart showed that the highest noise level is from the square cylinder at α = 45°. The directivity study shows that the noise level of the square cylinder at α = 45° at 90° angular location ( θ) is higher by 6.5 dB than that at θ = 30°.

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Aeroacoustics research in Europe: The CEAS-ASC report on 2019 highlights

Cited by 22 publications

References 64 publications

Recent Advances in Passive Acoustic Localization Methods via Aircraft and Wake Vortex Aeroacoustics

Recent Advances in Passive Acoustic Localization Methods via Aircraft and Wake Vortex Aeroacoustics

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

Aerodynamic noise characteristics of non-circular cylinders in subcritical flow regime

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