 Subjects -> AERONAUTICS AND SPACE FLIGHT (Total: 124 journals)
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- Generalized functions and acoustic analogy
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Authors: Jörgen Zillmann1276Munich; Germany
Abstract: International Journal of Aeroacoustics, Ahead of Print.
The aeroacoustic analogy is reviewed. The importance of generalized functions is demonstrated deriving Gauss like theorems in three and two dimensions. It is shown how the Dirac delta function plays an essential part in the theory of fundamental solutions ...
Citation: International Journal of Aeroacoustics
PubDate: 2025-04-04T04:43:56Z
DOI: 10.1177/1475472X251326972
- Effect of extending tip chord on the performance and noise of an axial
flow fan-
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Authors: Jiaming Wang; Haijiang He, Jinglong Liu, Kunfeng Liang, Aijin Zhou1Zhejiang Yilida Ventilator Co., Ltd, Taizhou, China2Henan University of Science Technology, Luoyang, China3Jiangsu Fulihua General Equipment Co., Ltd, Zhangjiagang, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
In this paper, the leakage flow in the blade tip clearance of an axial flow fan is studied, and an improved strategy for increasing the chord length of the blade tip toward the inflow direction is proposed. It has been proved that extending the tip chord ...
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-24T09:30:48Z
DOI: 10.1177/1475472X251326965
- Investigation of cavity flow noise attenuation using acoustic liners in
the locked-on state-
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Authors: Yuan Liu; Peiqing Liu, Hao Guo, Jiaming Ruan, Xu Chen1School of Aeronautic Science Information Technology, Beijing, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
The focus of this study is on utilizing acoustic liner technology to control the aerodynamic noise generated by cavities. The primary objective is to investigate the impact of these passive control measures on the coupled noise of low-speed cavity flows ...
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-20T02:53:19Z
DOI: 10.1177/1475472X251326973
- Aeroacoustic experiment and broadband noise model of contra-rotating
ducted fan under different rotating speeds-
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Authors: Hanru Liu; Qian Liu, Xun Shang, Hengde Liu, Siwei Wang, Yangang WangSchool of Power Energy,26487Northwestern Polytechnical University, Xi’an, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
Compared to a single rotor fan, a contra-rotating ducted fan (CRDF) has more power output per unit volume and can effectively reduce the weight of propulsor. However, contra-rotating turbomachinery has a stronger aerodynamic interaction between fan rows, ...
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-19T12:04:29Z
DOI: 10.1177/1475472X251326966
- Effect of incoming flow turbulence intensity on rod-airfoil aerodynamic
interaction noise-
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Authors: Fukang Huang; Zhongkun Jin1Key Laboratory of Noise Vibration Research, Institute of Acoustics, Chinese Academy of Sciences, Beijing, China2University of Chinese Academy of Sciences, Beijing, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
The effect of incoming turbulence intensity on the aerodynamic interaction noise of a rod-airfoil configuration is investigated by compressible large eddy simulation and Ffowcs Williams–Hawkings equation. The inlet position of the computational domain is ...
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-18T12:44:58Z
DOI: 10.1177/1475472X251326974
- Transient vibration and noise characteristics of on/off valve under high
frequency opening and closing-
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Authors: Hui Huang; Xin Luo, Wenli Liu, Yuzheng Li, Jianping Sun, Junshou Su112423School of Mechanical Engineering Intelligent Electro-Hydraulic Control, 12423Fuzhou University, Fuzhou, China3Jiangsu XCMG State Key Laboratory Technology Co., Ltd., Xuzhou, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
High-speed on/off valve (HSV) generates noise and vibration due to high-frequency collisions between internal components and fluid pressure impacts. In order to reveal the principle and characteristics of HSV noise generation, this study establishes the ...
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-17T08:10:50Z
DOI: 10.1177/1475472X251326964
- Computational aeroacoustic study of small three and four blade helical
vertical axis wind turbines in turbulent flow-
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Authors: Seyed Yousef Sajadi; Zeinab PouransariDepartment of Mechanical Engineering, 56944Iran University of Science Technology, Tehran, Iran
Abstract: International Journal of Aeroacoustics, Ahead of Print.
Aeroacoustic analysis of a small vertical-axis Darrieus wind turbine suitable for urban area applications is performed using numerical simulation and acoustic analogy. The analysis is performed for two helical wind turbine models with three- and four-...
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-15T04:16:03Z
DOI: 10.1177/1475472X251326963
- Guest Editor Biography
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Abstract: International Journal of Aeroacoustics, Ahead of Print.
Citation: International Journal of Aeroacoustics
PubDate: 2025-03-14T06:53:28Z
DOI: 10.1177/1475472X251327557
- Corrigendum to “Aerodynamic and aeroacoustic characteristics of rocket
sled under strong ground effect”-
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Abstract: International Journal of Aeroacoustics, Ahead of Print.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-21T03:53:23Z
DOI: 10.1177/1475472X241310586
- Control of fan broadband noise through wavy leading and trailing edge
serrations-
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Authors: S Narayanan, Sushil Kumar Singh, Manish Kant, Aadit Narayanmurthy; Sushil Kumar Singh, Manish Kant, Aadit NarayanmurthyDepartment of Mechanical Engineering, 28692Indian Institute of Technology (Indian School of Mines), Dhanbad, India
Abstract: International Journal of Aeroacoustics, Ahead of Print.
The present study provides comprehensive experimental investigations into the use of wavy leading edge (LE) and trailing edge (TE) serrations as a passive means for augmenting the reductions of fan broadband noise. The findings clearly indicate that the wavy LE – TE serrated fan could yield greater noise reduction performance than the un-serrated and wavy LE serrated fan, over a wide range of frequencies. In general, the wavy LE-TE serrated fans offer a maximum noise reduction of about 10 - 6 dB and an average reduction of about 4 - 5 dB, over a broad range of frequencies. For the range of frequencies from about 3 to 8 kHz, the wavy LE – TE serrated fan delivers a notable additional noise reductions of about 1-2 dB as compared to LE serrated ones, which is observed for all rpm values. For all rpm values, the un-serrated and serrated fans exhibit maximum / minimum directivity at an emission angle of about 127.5o / 77.5o. The lower far-field acoustic emissions (i.e., interaction noise + self-noise) offered by the wavy LE-TE serrated fans arises due to intense far-field destructive interference as a result of the faster spanwise phase variation of the velocity/pressure as well as the higher spanwise de-coherence. Further, the wavy LE-TE serrations mitigate direct scattering at both the LE and TE by dispersing sound energy over a wider area, which results in less intense noise signature in the far field. Thus, it clearly demonstrates that the second generation wavy LE-TE serrations could provide the substantial reduction of the far-field noise as compared to first-generation wavy serrations over a broad range of frequencies.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-19T07:14:30Z
DOI: 10.1177/1475472X241306316
- Large-eddy simulations of noise reduction via fundamental-harmonic
interactions in a supersonic rectangular jet-
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Authors: Benjamin J Malczewski, Saman Salehian, Vladimir V Golubev, Reda R Mankbadi; Saman Salehian, Vladimir V Golubev, Reda R Mankbadi1Department of Aerospace Engineering, 2830Embry-Riddle Aeronautical University, Daytona Beach, FL, USA2Department of Aerospace Science Engineering, 8066Tuskegee University, Tuskegee, AL, USA
Abstract: International Journal of Aeroacoustics, Ahead of Print.
This work explores the use of bi-modal excitation to reduce the noise in a supersonic rectangular jet. The excitation is guided by previously published reduced-order modelling, suggesting that harmonic interactions can reduce the dominant noise sources in the jet. An unexcited jet is considered first as the baseline case, which showed Strouhal number 0.15 as the most dominant near field coherent structure, which also appeared as a prominent peak in the far field noise at low emission angles and as a secondary peak at the peak emissivity angle, thus it was taken as the fundamental frequency to target with excitation. The jet is then excited with the single-mode harmonic, St 0.30. Other cases are considered with bi-modal excitation at St’s 0.15 and 0.30 with various phase lags. Both single-mode and bi-modal excitation show a considerable reduction of the near field coherent structures at St 0.15 and amplification at 0.30. Reduction of the fundamental in the bi-modal cases shows a dependence on the initial phase lag whereby reduction is maximized when harmonic amplification is maximized. All excited cases are also shown to reduce the eddy convection velocity. Reduction in far field sound pressure levels at St 0.15 is obtained for all excitation cases up to 13 dB. For all metrics, it is shown that bi-modal excitation is more effective than single-mode excitation given an optimized phase lag. All results ultimately support the use of fundamental-harmonic interactions as a noise reduction mechanism.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-13T10:47:45Z
DOI: 10.1177/1475472X241306337
- Axisymmetric cavity noise control using passive protrusion
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Authors: Kabilan Baskaran, Kothandaraman Srinivasan; Kothandaraman Srinivasan1Department of Mechanical Engineering, 28692Indian Institute of Technology (Indian School of Mines), Dhanbad, India2Department of Mechanical Engineering, 37268Indian Institute of Technology Madras, Chennai, India
Abstract: International Journal of Aeroacoustics, Ahead of Print.
This paper introduces a passive protrusions to reduce undesirable structural loading and high-amplitude noise radiation in axisymmetric cavities, are common in industries, including pipelines and aerospace. A comprehensive experimental investigation of the pipe-cavity noise control system is conducted, exploring various protrusion locations and lengths at different Nozzle Pressure Ratios (NPRs). The study examines protrusions placed at the leading, trailing, and both leading and trailing edges of the axisymmetric cavity. Additionally, detailed experiments are performed to analyze the impact of protrusion lengths on unsteady cavity pressure and far-field noise radiation. Cavity pressure fluctuations and far-field noise levels are measured for both cases: with and without protrusions in the pipe-cavity setup. The Proper Orthogonal Decomposition (POD) technique is applied to the time-resolved Schlieren images to show the effect of passive protrusions on the exit jet flow structure. Results demonstrate that a protrusion located at the trailing edge yields superior noise reduction compared to other configurations. The efficacy of this protrusion in mitigating cavity noise is attributed to its ability to efficiently alleviate the feedback mechanism responsible for cavity noise generation and break down the recirculation region within the cavity system. Significant noise reduction, approximately 4 dB, is achieved at lower NPRs, and substantial noise reductions are also observed for the underexpanded jet condition.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-11T12:02:42Z
DOI: 10.1177/1475472X241306313
- On the relationship between acoustic absorption and temperature gradient
in a thermoacoustic liner-
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Authors: Samarjith Biswas, William Kresl, James M Manimala; William Kresl, James M ManimalaSchool of Mechanical Aerospace Engineering, 7618Oklahoma State University, Stillwater, OK, USA
Abstract: International Journal of Aeroacoustics, Ahead of Print.
The thermoacoustic effect provides a means to convert acoustic energy to heat and vice versa without the need for moving parts. This makes thermoacoustic devices of interest for multifunctional applications in harsh or remote service environments. Embedding thermoacoustic stacks within the framework of acoustic liners could provide opportunities to simultaneously optimize both acoustic absorption and thermal output as well as to integrate energy harvesting and sensing and monitoring functionalities. In this study, the influence of sound pressure level and frequency as well as stack length and position on the performance of a thermoacoustic liner is investigated using normal incidence impedance tube tests and DeltaEC simulations. Using Rott’s approximation, the stack’s pore width and wall thickness are optimized for additively manufactured thermoacoustic liner test articles. A peak steady-state temperature gradient of 9.5°C is obtained at 790 Hz for 140 dB tonal dwells. It is found that the temperature gradient correlates directly with the acoustic power available at the leading stack-face, which is highest when the stack is near the center of the resonator. In contrast, acoustic absorption diminishes when the stack is nearer to the closed-end of the resonator. At higher excitation pressure levels, the contribution of viscous heating to the deviation in the thermoacoustic gradient becomes significant. Further, the relationship between the acoustic absorption and the thermoacoustic temperature gradient was examined. In application scenarios requiring multifunctional optimization, a tradeoff may be required in terms of the absorption in order to maximize the temperature gradient. With current additive and hybrid fabrication processes and materials reaching commercial maturity, opportunities exist to realize thermoacoustic liners with enriched functionalities.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-11T08:11:39Z
DOI: 10.1177/1475472X241306317
- Numerical investigation on aerodynamic noise of rigid coaxial rotor in
forward flight with lift-offset-
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Authors: Haotian Qi, Linsong Jiang, Tianmei Pu, Weijun Zhu; Linsong Jiang, Tianmei Pu, Weijun Zhu1College of Electrical, Energy Development Center, Mianyang, China3School of Mechanical Engineering, 91588Liaoning Technical University, Fuxin, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
A computational fluid dynamics (CFD) solver based on Reynolds-averaged Navier–Stokes (RANS) equations and high-efficiency trim model is used to simulate the unsteady aerodynamics of coaxial rotor. Farassat 1 A equations are adopted for predicting rotor far-field aerodynamic noise. Forward flight cases of a two-bladed rigid coaxial rotor in different advance ratios and lift-offsets (LOS) are conducted. Sound pressure histories of different observation points and noise radiation maps are analyzed. Results indicate that, the intensity of rotor thickness noise moves towards the advancing side in the rotor disk plane, with the increase of advance ratio. Due to the superposition effect, the thickness noise of coaxial rotor is symmetrical, which is different with the single rotor. At low advance ratio, loading noise of the rigid coaxial rotor is enhanced near the blade-crossing azimuths caused by the unsteady interaction of the twin rotors. The enhancement turns weak with the increase of advance ratio. At high advance ratio, increasing LOS tends to enhance the rotor-self BVI noise, while weakening the inter-rotor interaction noise. At certain flight states, appropriate LOS can reduce the overall noise radiation intensity of rigid coaxial rotor.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-07T12:17:43Z
DOI: 10.1177/1475472X241306336
- Guest editor biography
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Abstract: International Journal of Aeroacoustics, Ahead of Print.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-03T02:06:01Z
DOI: 10.1177/1475472X241306930
- Guest editor biography
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Abstract: International Journal of Aeroacoustics, Ahead of Print.
Citation: International Journal of Aeroacoustics
PubDate: 2024-12-02T01:15:52Z
DOI: 10.1177/1475472X241306929
- Computational study on aerodynamic noise reduction of high-speed train
bogie region using leading edge jet of the bogie cavity-
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Authors: Jiawei Shi, Jiye Zhang, Tian Li; Jiye Zhang, Tian LiState Key Laboratory of Rail Transit Vehicle System, 56711Southwest Jiaotong University, Chengdu, China
Abstract: International Journal of Aeroacoustics, Ahead of Print.
This study employs a numerical approach that combines compressible detached eddy simulation (DES) with the Ffowcs Williams-Hawkings (FW-H) equation to investigate the potential of employing a slot jet at the leading edge of the bogie cavity for reducing bogie aerodynamic noise. The simulation is conducted on a 1:8 scale shortened train model, and two jet fluxes are considered. The permeable surface formula of the FW-H equation is adopted for far-field noise calculation to account for the scattering and shielding effects of the vehicle body and track structures, as well as the quadrupole source contribution. The results reveal that the slot jet induces a notable lifting effect on the shear layer formed at the leading edge of the bogie cavity, consequently reducing the impact of the shear vortex structures on the lower part of the bogie and the rear wall of the bogie cavity. However, as the shear vortex structures are guided towards the track, their interactions with the track structures are intensified. Due to the slow attenuation of the turbulent wake of the bogie region, it is difficult to avoid the spurious sound sources (hydrodynamic pressure fluctuations) induced by the wake passing through the integral surface by merely adjusting the position of downstream integral surface, while the end cap averaging technology can effectively filter out these spurious sources. The introduction of the jet primarily reduces the far-field noise below 1600 Hz of the bogie region, with higher jet velocity resulting in improved noise reduction effects.
Citation: International Journal of Aeroacoustics
PubDate: 2024-11-28T07:33:26Z
DOI: 10.1177/1475472X241306330
- Jet noise sources for chevron nozzles in under-expanded condition
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Authors: Hasan Kamliya Jawahar, Stefano Meloni, Roberto Camussi; Stefano Meloni, Roberto Camussi1Department of Aerospace Engineering, University of Bristol, Bristol, UK2Department of Engineering, University of Roma Tre, Rome, Italy
Abstract: International Journal of Aeroacoustics, Ahead of Print.
Imperfectly expanded jet flows are known to have additional noise sources known as Screech and broadband shock-associated noise. They are generated by the interaction between the instability waves that propagate from the lip of the nozzle and the shock cell structures. In this study, thorough experimental investigations were carried out on chevron nozzles to assess the importance of chevron parameters such as the chevron count and chevron penetration angle on the pressure field emitted by the jet. Data were acquired in the state-of-the-art aeroacoustic facility at the University of Bristol. Acoustic measurements such as pressure spectra, directivity and overall sound pressure levels along with near-field measurements were acquired for jet Mach numbers ranging from M = 1.1–1.4. Fourier-based and Wavelet-based analyses were used to highlight the different features of the various tested nozzles. Wavelet decomposition results highlight that the presence of the chevrons reduce the acoustic noise especially at a higher axial distance with increased levels of noise reduction achieved by chevron nozzle with deep penetration angle.
Citation: International Journal of Aeroacoustics
PubDate: 2022-06-21T06:18:18Z
DOI: 10.1177/1475472X221101766
- Corrigendum to The effect of the convective momentum transfer on the
acoustic boundary condition of perforated liners with grazing mean flow-
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Abstract: International Journal of Aeroacoustics, Ahead of Print.
Citation: International Journal of Aeroacoustics
PubDate: 2022-04-12T03:00:03Z
DOI: 10.1177/1475472X221096743
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Hybrid journal (It can contain Open Access articles)
