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1
Fabrizi, Carlo. « Computational Aeroacoustic Analysis of a Rolling Tire ». Tire Science and Technology 44, no 4 (1 octobre 2016) : 262–79. http://dx.doi.org/10.2346/tire.16.440403.
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ABSTRACT Road traffic is one of the major sources of noise in modern society. Consequently, the development of new vehicles is subject to increasingly stringent guidelines in terms of noise emissions. The main noise sources of common road vehicles are the engine, the transmission, the aerodynamics, and the tire-road interaction. The latter becomes dominant between 50 and 100 km/h, speeds typical of urban and extra-urban roads. The noise that arises from the tire-road interaction is the combination of structural vibration and aeroacoustics phenomena that create and amplify or reduce the sound emitted from the tire. The aim of the numerical analysis presented in this study is to investigate the aeroacoustic noise-generation mechanisms of the tire and at the same time provide a tool to develop a low-noise tire. The work is divided into two parts: analysis of the steady aerodynamics and the unsteady aeroacoustic analysis. In the first part, the numerical solution of the Navier-Stokes equation allows us to screen aerodynamic phenomena, such as separations or jet streams that can produce noise. In the second part, these aspects are analyzed in greater detail by means of aeroacoustic analogies, confirming the capability of the numerical tool to provide suggestions for the development of quieter tires.
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Joshi, Arnav, Mustafa M. Rahman et Jean-Pierre Hickey. « Recent Advances in Passive Acoustic Localization Methods via Aircraft and Wake Vortex Aeroacoustics ». Fluids 7, no 7 (29 juin 2022) : 218. http://dx.doi.org/10.3390/fluids7070218.
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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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Vouros, Stavros, Ioannis Goulos, Calum Scullion, Devaiah Nalianda et Vassilios Pachidis. « Impact of Tip-Vortex Modeling Uncertainty on Helicopter Rotor Blade–Vortex Interaction Noise Prediction ». Journal of the American Helicopter Society 66, no 1 (1 janvier 2021) : 1–13. http://dx.doi.org/10.4050/jahs.66.012005.
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Free-wake models are routinely used in aeroacoustic analysis of helicopter rotors; however, their semiempiricism is accompanied with uncertainty related to the modeling of physical wake parameters. In some cases, analysts have to resort to empirical adaption of these parameters based on previous experimental evidence. This paper investigates the impact of inherent uncertainty in wake aerodynamic modeling on the robustness of helicopter rotor aeroacoustic analysis. A free-wake aeroelastic rotor model is employed to predict high-resolution unsteady airloads, including blade–vortex interactions. A rotor aeroacoustics model, based on integral solutions of the Ffowcs Williams–Hawkings equation, is utilized to calculate aerodynamic noise in the time domain. The individual analytical models are incorporated into an uncertainty analysis numerical procedure, implemented through nonintrusive Polynomial Chaos expansion. The potential sources of uncertainty in wake tip-vortex core growth modeling are identified and their impact on noise predictions is systematically quantified. When experimental data to adjust the tip-vortex core model are not available the uncertainty in acoustic pressure and noise impact at observers dominated by blade–vortex interaction noise can reach up to 25% and 3.50 dB, respectively. A set of generalized uncertainty maps is derived, for use as modeling guidelines for aeroacoustic analysis in the absence of the robust evidence necessary for calibration of semiempirical vortex core models.
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Ragni, Daniele, Francesco Avallone et Damiano Casalino. « Measurement techniques for aeroacoustics : from aerodynamic comparisons to aeroacoustic assimilations ». Measurement Science and Technology 33, no 6 (9 mars 2022) : 062001. http://dx.doi.org/10.1088/1361-6501/ac547d.
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Abstract Sustainability has encouraged studies focusing on lowering the aeroacoustic impact of new aerodynamically optimized mechanical systems for several applications in wind-energy, aviation, automotive and urban air-mobility. The deployment of effective noise-reduction strategies starts with a deep understanding of the underlying mechanisms of noise generation. To elucidate the physics behind the onset of aerodynamic sources of sound, experimental techniques used for aerodynamic purposes have been combined with acoustic measurements. In the last decades, new experimental post-processing techniques have additionally been developed, by leveraging aeroacoustic analogies in a new multi-disciplinary framework. New approaches have been proposed with the intent of translating near-field velocity and pressure information into sound. The current review describes how such breakthroughs have been achieved, briefly starting from a historical overview, to quickly bridge to the measurement techniques and the facilities employed by the scientific community. Being the measurement principles already reported in the literature, this review only focuses on the most relevant studies trying to relate the near-field information to the perceived sound in the far-field. Aspects related to the uncertainty of the measurement techniques will be thus very briefly discussed, together with their relation to the background noise of the testing facilities, including acoustic reflections/refractions, and issues related to the instrumentation.
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Perugini, Carlo Alberto, Ugo Riccio, Antonio Torluccio, Rouven Mohr, Reinhard Blumrich et Andreas Wagner. « An Efficient Hybrid Computational Process for Interior Noise Prediction in Aeroacoustic Vehicle Development ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 266, no 2 (25 mai 2023) : 829–38. http://dx.doi.org/10.3397/nc_2023_01_1120.
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Numerical methodologies for aeroacoustic analyses are increasingly crucial for car manufacturers to optimize the effectiveness of vehicle development. In the present work, a hybrid numerical tool based on the combination of a delayed detached-eddy simulation and a finite element model, which relies on the Lighthill's acoustic analogy and the acoustic perturbation equations, is presented. The computational aeroacoustics is performed by the software OpenFOAM and Actran, concerning respectively the CFD and the FEM. The aeroacoustic behavior of the SUV Lamborghini Urus at a cruising speed of 140 km/h has been investigated. The main aerodynamic noise phenomena occurring in the side mirror region in a frequency range up to 5 kHz are discussed. The numerical simulations have been verified against the measurements performed in the aeroacoustic wind tunnel of the University of Stuttgart, operated by FKFS. The predicted exterior noise propagation into the far field has been validated by comparing the sound pressure level with the experimental data measured by exterior microphones, which were located outside the turbulent region beside the wake of the side mirror. Furthermore, the noise transmission into the cabin through the side window has been modeled. Simulation results have been validated by means of interior microphones installed on the driver seat. Both the exterior and the interior noise predictions show very good correlations with experiments. Lastly, a comprehensive investigation of the most critical aeroacoustic sources has been carried out. The numerical tool has been proven to be in good accordance with the microphone array with respect to the distribution of the sound pressure level in the proximity of the side mirror. Besides, the main vortex structures involved in the generation mechanisms of wind noise have been investigated by a CFD analysis. The entire CAA process has been proven to be accurate and suitable for combined analysis between the generation mechanisms of wind noise and the resulting transfer into the interior cabin to the driver's ear as well.
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Klimczyk, Witold, et Adam Sieradzki. « RANS-Based Aeroacoustic Global Sensitivity Study and Optimization of UAV Propellers ». Aerospace 10, no 3 (20 mars 2023) : 306. http://dx.doi.org/10.3390/aerospace10030306.
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Modeling of Unmanned Aerial Vehicles (UAV) propellers in a global, multidisciplinary aeroacoustic optimization was investigated. The modeling consists of three aspects: geometry, aerodynamics, and aeroacoustics. Firstly, a parametric geometry model was established using chord, twist, and sweep distributions along the radius, defined by splines to ensure smoothness. Additionally, airfoil parameters including maximum camber and its position, as well as the position of maximum thickness, were added. Secondly, a blade geometry-resolved aerodynamic model based on steady RANS was established. A two-equation SST turbulence model was used for compressible flow with periodic boundary conditions. Thirdly, an aeroacoustic model for far-field tonal noise calculation was defined, based on the Ffowcs Williams and Hawkings analogy and a RANS solution. A global sensitivity analysis was performed to establish the importance of individual design variables. Consequently, surrogate modeling-based optimization strategy was devised to efficiently establish Pareto front of propeller geometries in multi-objective aeroacoustic optimization.
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Schoder, Stefan, et Manfred Kaltenbacher. « Hybrid Aeroacoustic Computations : State of Art and New Achievements ». Journal of Theoretical and Computational Acoustics 27, no 04 (décembre 2019) : 1950020. http://dx.doi.org/10.1142/s2591728519500208.
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This paper collects the state of the art and the tremendous progress that has been made in hybrid modeling of aeroacoustic sound. Hybrid modeling is defined such that flow and acoustics are modeled separate and connected by an aeroacoustic model. The contributions will be classified with respect to the aeroacoustic models being developed, covering Lighthill’s analogy, Ffowcs Williams and Hawkings, vortex sound, linearized Euler equations (LEE), and different perturbation equations modeling flow induced sound. Within each topic, specific applications, such as jet noise, aircraft noise, ground mobility, noise, fan noise and human phonation, are covered. We focus on the accomplishments and provide the authors’ contribution to aeroacoustic research. Eventually, a concise summary of the different methods and their capabilities is included.
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Cai, Jian Cheng, Yong Hai Zhang et Shuang Li Long. « Computational Estimation of Fan Casing Noise at Blade Passing Frequency Component Noise ». Applied Mechanics and Materials 184-185 (juin 2012) : 95–100. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.95.
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This paper studies both vibroacoustics and aeroacoustics of a centrifugal fan casing; the aim of this study is to explore a methodology to make quantitative predictions of fan casing noise. The spectra of the fan noise and casing vibration were firstly presented; discrete components related to the rotational frequency protrude in the spectra, especially the blade passing frequency (BPF). Computational fluid dynamics (CFD) technique was used to obtain the three-dimensional unsteady turbulent internal flow. Attention was paid to the pressure fluctuations on the volute wall; the shapes of pressure fluctuation were nearly sinusoidal in nature, with the BPF as the primary frequency. On the vibroacoustic side, Fast Fourier Transform (FFT) was applied to the time series of pressure fluctuations to extract the BPF component. A finite element analysis (FEA) model of the casing structure was constructed, and was validated by experimental modal analysis. The harmonic dynamic response of the casing structure was calculated with the BPF pressure fluctuation component as the excitation. The vibration results were then taken as the velocity (Neumann) boundary condition for the noise radiation model which was built in boundary element method (BEM), and the sound radiation was calculated. On the aeroacoustic side, the BPF component of pressure fluctuations was modeled as acoustic dipole source, and sound radiation was also solved by BEM. Results show that the sound pressure level (SPL) of vibroacoustics is fairly small compared to the aeroacoustic counterpart. This study shows that CFD, FEA together with BEM can be used to numerically predict BPF casing noise of turbomachinery successfully.
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Staron, Domenic, Matthias Riegel, Reinhard Blumrich et Andreas Wagner. « Aeroacoustic Vehicle Development Method Considering Realistic Wind Conditions ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 266, no 2 (25 mai 2023) : 858–66. http://dx.doi.org/10.3397/nc_2023_01_1123.
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The aeroacoustic development of vehicles is still mainly carried out in wind tunnels under steady flow conditions, although the real situation is different. However, as discussed in several earlier publications, a vehicle experiences unsteady, turbulent flow on road, which results for example from natural wind, wakes of other vehicles, or obstacles at the roadside in combination with side wind. The resulting temporal variations of the wind noise inside the cabin affect the passengers' comfort and safety through fatigue. To be able to also consider the unsteady aeroacoustics in the vehicle development process, a comprehensive method has been developed that is presented in full for the first time in this paper. The on-road situation is simulated in a realistic and reproducible manner in the full-scale wind tunnel of the University of Stuttgart by means of an active turbulence generator, developed by FKFS. The turbulence generator allows to dynamically vary the flow angle with frequency components of up to 10 Hz. By comparing the unsteady wind noise for different flow situations and different vehicles, a flow scenario has been derived which leads to representative and meaningful aeroacoustic results. The measured temporal wind noise variations are investigated using modulation analysis, which has been adapted to show only relevant information in a comprehensible way. Finally, a psychoacoustic metric for rating the annoyance of unsteady, as well as steady, wind noise has been developed based on listening studies. The metric describes the subjective perception and allows evaluation and optimization of the aeroacoustic behavior specifically regarding the passengers' comfort. With this new method all wind noise aspects, steady as well as unsteady, can be determined and taken into account for vehicle development. The evaluation and comparison of vehicles and variants is comprehensive and is focused on the passengers' comfort.
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Ji, Chun Hui, et Zhan Qiang Liu. « Aeroacoustic Performance Evaluation of Milling Cutters Based on the Flow Field on the Cutter Surface ». Advanced Materials Research 188 (mars 2011) : 398–403. http://dx.doi.org/10.4028/www.scientific.net/amr.188.398.
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Many workers all over the world suffer significant hearing loss as well as psychological and physical stress as a result of exposure to high levels of aeroacoustic noise. Dipole sources are the major noise sources in aeroacoustic noise generation in rotating face milling cutters. A noise model based on the Ffowcs Williams-Hawkings Equation is used to predict aeroacoustic noise; the noise predicted was 2.5dB less than the experimental observations. Flow field of cutter surface was numerically simulated by the resolution of the Navier-Stokes equations (CFD) and five zones on cutter surface were founded to be the important noise source. The broadband noise spreads over a broad range of frequencies and contributes significantly to overall noise, but the discrete noise at the rotational frequency is usually higher and more detrimental to the body.
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Borghi, Fabrício Torres, José Eduardo Mautone Barros et Ramon Molina Valle. « Aeroacoustics Investigation of an Automotive Exhaust Muffler ». Advanced Materials Research 1016 (août 2014) : 529–33. http://dx.doi.org/10.4028/www.scientific.net/amr.1016.529.
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Traffic is a major source of environmental noise in modern society. Subsequently, the development of new vehicles is subjected to heavy governmental legislations. The major noise source on common road vehicles during acceleration is the flow noise caused by turbulent exhaust gas. The main goal of this work is to develop an appropriate Aeroacoustic simulation method to investigate the acoustic of sound on exhaust automotive muffler. The range of validity of the method is studied comparing results to experimental data. The Computational Aeroacoustics (CAA) results are compared with an experimental test in a vehicle during its acceleration and the mean flow model of the muffler has a satisfactory mesh with a suitable inlet boundary provided by an engine dynamometer data. The present work describes a good agreement between computational and experimental approach for the Aeroacoustics behavior of a specific configuration of exhaust muffler.
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Stuermer, A., J. Yin et R. Akkermans. « Progress in aerodynamic and aeroacoustic integration of CROR propulsion systems ». Aeronautical Journal 118, no 1208 (octobre 2014) : 1137–58. http://dx.doi.org/10.1017/s0001924000009829.
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Abstract Contra-Rotating Open Rotor (CROR) propulsion systems have seen renewed interest as an economic and environmentally friendly powerplant for future transport aircraft. Installation effects, i.e. the mutual interactions between airframe components and the rotors, have a pronounced impact on the aerodynamic and aeroacoustic performance for this type of engine. In the past five years, DLR’s Institute of Aerodynamics and Flow Technology has performed a number of numerical studies investigating important aspects relating to engine-airframe integration of CROR engines. In this article an overview of coupled aerodynamic and aeroacoustic simulations investigating representative pusher-configuration CROR engines will be given, focusing on the impact on aerodynamic performance and aeroacoustics caused by the presence of a pylon, the potential for noise reduction by employing trailing-edge blowing at the pylon trailing edge as well as the performance and noise variations caused by different senses of rotation of the rotors. It is shown that the interaction with the pylon strongly impacts blade performance and front rotor noise emissions but that the use of active flow control in the form of pylon trailing-edge blowing can alleviate these adverse installation effects to a notable extent.
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Zhao, Zhiheng, Weijie Chen et Cheng Yang. « An efficient hybrid aeroacoustic method to predict the noise of a ducted coaxial-rotor UAV ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, no 7 (30 novembre 2023) : 1443–48. http://dx.doi.org/10.3397/in_2023_0216.
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Ducted coaxial-rotor UAV is a new concept UAV configuration. Compared with the traditional open rotor UAV, it has the advantages of higher safety, lower noise and smaller size, especially suitable for compact space and low noise scene applications. However, the complexity of the internal flow field caused by the presence of the duct makes it difficult to obtain accurate acoustic results by using the conventional aeroacoustic simulation methods. Based on the theory of duct acoustics and the theory of propeller noise, this paper presents an efficient calculation method of aeroacoustic source suitable for the configuration of a ducted UAV. The aeroacoustic source of a ducted coaxial-rotor UAV independently developed by the current research group is studied, and the duct acoustic mode components excited by the aeroacoustic source of the UAV are obtained. The results show that the distribution of the duct mode excited by the aeroacoustic source of the ducted UAV has a strong correlation with the number of propeller blades, and the main characteristic modes dominate the acoustic source of the UAV.
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Asheim, Michael, Paul Papas, Patrick Moriarty et Jon Collis. « Wind turbine aeroacoustic noise and noise mitigation strategies. » Journal of the Acoustical Society of America 128, no 4 (octobre 2010) : 2285. http://dx.doi.org/10.1121/1.3508009.
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Sun, Jianwei, Koichi Yonezawa, Eiji Shima et Hao Liu. « Integrated Evaluation of the Aeroacoustics and Psychoacoustics of a Single Propeller ». International Journal of Environmental Research and Public Health 20, no 3 (20 janvier 2023) : 1955. http://dx.doi.org/10.3390/ijerph20031955.
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Aeroacoustic noise in multiple rotor drones has been increasingly recognized as a crucial issue, while noise reduction is normally associated with a trade-off between aerodynamic performance and sound suppression as well as sound quality improvement. Here, we propose an integrated methodology to evaluate both aeroacoustics and psychoacoustics of a single propeller. For a loop-type propeller, an experimental investigation was conducted in association with its aerodynamic and acoustic characteristics via a hover stand test in an anechoic chamber; the psychoacoustic performance was then examined with psychoacoustic annoyance models to evaluate five psychoacoustic metrics comprising loudness, fluctuation strength, roughness, sharpness, and tonality. A comparison of the figure of merit (FM), the overall sound pressure level (OASPL) and psychoacoustic metrics was undertaken among a two-blade propeller, a four-blade propeller, the loop-type propeller, a wide chord loop-type propeller, and a DJI Phantom III propeller, indicating that the loop-type propeller enables a remarkable reduction in OASPL and a noticeable improvement in sound quality while achieving comparable aerodynamic performance. Furthermore, the psychoacoustic analysis demonstrates that the loop-type propeller can improve the psychological response to various noises in terms of the higher-level broadband and lower-level tonal noise components. It is thus verified that the integrated evaluation methodology of aeroacoustics and psychoacoustics can be a useful tool in the design of low-noise propellers in association with multirotor drones.
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Dixon, Rowena, Chaoyang Jiang, Charitha de Silva, Danielle Moreau et Con Doolan. « Tandem cylinder aeroacoustic sources ». Journal of the Acoustical Society of America 154, no 4_supplement (1 octobre 2023) : A330. http://dx.doi.org/10.1121/10.0023703.
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Tandem cylinders in turbulent flow are found in aircraft landing gear, chimney stacks, power lines, and bridge piers. The aim of this paper is to present detailed unsteady surface pressure measurements for tandem cylinders. These unsteady surface pressures are the major sources of noise in this important fundamental test case. A series of experiments were conducted in the UNSW anechoic wind tunnel to investigate the sound generation and flow distortion from a downstream cylinder interacting with wake from an upstream cylinder. This wake is highly anisotropic, containing large vortex shedding scales as well as energetic broadband components. The experiments were conducted using PIV (Particle Image Velocimetry) to obtain instantaneous flow fields and remote microphones to capture unsteady surface pressure measurements. Microphones were positioned outside the flow to record far-field noise. The cylinder was rotated to obtain surface pressure around the circumference. The acoustic results for the tandem cylinder case were compared with noise generation from a single cylinder in uniform flow. An increase in both surface pressure and far-field noise was observed in the tonal and broadband components. It was concluded that interaction with the wake of the upstream cylinder significantly increased the unsteady surface pressure of the downstream cylinder.
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Tychsen, Jörn, et Joachim Rösler. « Production and characterization of experimental low noise trailing edges made of cold rolled porous aluminum with special attention to the influence of cold rolling on the mechanical stability of the investigated materials ». CEAS Aeronautical Journal 12, no 3 (31 mai 2021) : 573–87. http://dx.doi.org/10.1007/s13272-021-00519-5.
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AbstractIn the framework of the CRC 880 “Fundamentals of high-lift for future civil air craft” methods for the reduction of aircraft noise are investigated. An important method for this noise reduction is the usage of porous material as low noise trailing edges. To improve the aeroacoustic properties of porous materials, an innovative rolling process was established by Tychsen et al. (Metals 8:598, 2018). Here, the rolling process is described as it is used as an important method for the production of samples. The influence of cold rolling on two different porous materials namely porous aluminum 80–110 (PA 80–110) and PA 120–150 is investigated. Important characteristics studied are the porosity, mechanical properties and the dependence of flow resistivity from the degree of deformation. The flow resistivity is of particular interest as the aeroacoustic performance is significantly influenced by it. The results are then compared to the findings for PA 200–250, which was investigated in Tychsen et al. (Metals 8:598, 2018). Lastly, experimental trailing edges made out of cold rolled porous aluminum with a gradient in thickness reduction are shown. The characterization of the aeroacoustic behavior is not part of this study. Reference is made to Rossignol et al. (Int J Aeroacoust 19:365–384, 2020), where trailing edges shown here are characterized aeroacoustically. The findings shown here demonstrate that different porous materials can be tailored by cold rolling without negative impact on the mechanical behavior. It is proven that the new rolling process is a versatile tool for the production of gradient porous material.
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Dinulovic, Mirko, Marta Trninic, Bosko Rasuo et Dejan Kozovic. « Methodology for aeroacoustic noise analysis of 3-bladed h-Darrieus wind turbine ». Thermal Science 27, no 1 Part A (2023) : 61–69. http://dx.doi.org/10.2298/tsci2301061d.
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The present paper presents the aeroacoustic calculation methodology for the H-Darrieus wind turbine. The CFD analysis, for different wind turbine blades? angles of attack, coupled with the noise analysis, based on Lighthill and Prudmann models is performed. This type of turbine is of particular interest since it is insensitive to wind direction and can be used in urban areas. In this study commercial software, ANSYS is used for CFD and aeroacoustic analysis. The required turbulent flow field is calculated based on the standard k-? model, and reequired model constants are obtained experimentally in a low-Mach number wind tunnel. The noise levels generated by operating turbine are calculated based on Lighthill and Proudman's aeroacoustic theories. It was found that the methodology presented can be efficiently used in noise analysis of vertical axes wind turbines and due to recent strict noise regulations has to be deployed at the early design stages.
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Kennedy, J., O. Adetifa, M. Carley, N. Holt et I. Walker. « Aeroacoustic sources of motorcycle helmet noise ». Journal of the Acoustical Society of America 130, no 3 (septembre 2011) : 1164–72. http://dx.doi.org/10.1121/1.3621097.
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Namba, Masanobu, et Akihiro Murahashi. « Aeroacoustic Control of Fan Tone Noise ». AIAA Journal 46, no 1 (janvier 2008) : 54–60. http://dx.doi.org/10.2514/1.24586.
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Spehr, Carsten. « Expert decision support system to improve the analysis of airframe noise measurements ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, no 2 (30 novembre 2023) : 6578–84. http://dx.doi.org/10.3397/in_2023_0972.
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For the localization and estimation of aeroacoustic sources on complex aircraft models in wind tunnel measurements beamforming and related methods are well known. The task of the aeroacoustic experts is to identify and classify the relevant sources within these beamforming maps. In this paper, we present an expert decision support system to support this task. The system comprises three steps: The first step identifies aeroacoustic sources in sparse beamforming maps and extracts their corresponding spectra without manual definition of regions of interest. The second step calculates the acoustic properties of the sources based on spectral and spatial information. The third step clusters the identified sources based on these acoustic properties. In this paper, data are evaluated based on CLEAN-SC beamforming maps of two airframe half-model wind tunnel measurements. A variety of aeroacoustic features are proposed that capture the characteristics of the source spectra. The result of this expert decision support system is a list of all relevant sources clustered according to their acoustic behavior at different Mach numbers. The aim of the system is to support aeroacoustic specialists in analyzing beamforming results and identifying relevant and spurious sources in-situ.
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Yang, Guang Jun, Jian Jun Liu et Jing Sun. « Computational Aeroacoustic Simulation of Landing Gear ». Applied Mechanics and Materials 421 (septembre 2013) : 110–15. http://dx.doi.org/10.4028/www.scientific.net/amm.421.110.
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RANS / NLAS numerical simulation method is adopted in this paper to carry out study on the aerodynamic noise analysis of basic landing gear configuration. Reynolds average N-S equation is solved with nonlinear turbulence model to establish the landing gear initial flow field, based on which, the NLAS (nonlinear acoustic solver) processed the turbulence fluctuation reconstruction to obtain the near-field acoustic characteristics of landing gear. Combined with the flow characteristics and the associated noise spectrum analysis, aerodynamic noise characteristics of landing gear are achieved. The work in this paper can provide useful research foundation on the following noise reduction design of landing gear.
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Thai, Austin David, Elisa De Paola, Alessandro Di Marco, Luana Georgiana Stoica, Roberto Camussi, Roberto Tron et Sheryl Marie Grace. « Experimental and Computational Aeroacoustic Investigation of Small Rotor Interactions in Hover ». Applied Sciences 11, no 21 (26 octobre 2021) : 10016. http://dx.doi.org/10.3390/app112110016.
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This paper investigates the aeroacoustic interactions of small hovering rotors, using both experiments and computations. The experiments were conducted in an anechoic chamber with arrays of microphones setup to evaluate the azimuthal and polar directivity. The computational methodology consists of high fidelity detached eddy simulations coupled to the Ffowcs-Williams and Hawkings equation, supplemented by a trailing edge broadband noise code. The aerodynamics and aeroacoustics of a single rotor are investigated first. The simulations capture a Reynolds number effect seen in the performance parameters that results in the coefficient of thrust changing with the RPM. The acoustic analysis enables the identification of self-induced noise sources. Next, dual side-by-side rotors are studied in both counter-rotating and co-rotating configurations to quantify the impact of their interactions. Higher harmonics appear due to the interactions and it is verified that the counter-rotating case leads to more noise and a less uniform azimuthal directivity. Difficulties that arise when trying to validate small rotor calculations against experiments are discussed. Comparisons of computational and experimental results yield further insight into the noise mechanisms that are captured by each methodology.
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Kamliya Jawahar, Hasan, Syamir Alihan Showkat Ali et Mahdi Azarpeyvand. « Aeroacoustic analysis of slat tones ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 263, no 1 (1 août 2021) : 5650–63. http://dx.doi.org/10.3397/in-2021-3202.
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Experimental measurements were carried out to assess the aeroacoustic characteristics of a 30P30N high-lift device, with particular attention to slat tonal noise. Three different types of slat modifications, namely slat cove filler, serrated slat cusp, and slat finlets have been experimentally examined. The results are presented for an angle of attack of α = 18 at a free-stream velocity of U = 30 m/s, which corresponds to a chord-based Reynolds number of Re = 7 x 10. The unsteady surface pressure near the slat region and far-field noise were made simultaneously to gain a deeper understanding of the slat noise generation mechanisms. The nature of the low-frequency broadband hump and the slat tones were investigated using higher-order statistical approaches for the baseline 30P30N and modified slat configurations. Continuous wavelet transform of the unsteady surface pressure fluctuations along with secondary wavelet transform of the broadband hump and tones were carried out to analyze the intermittent events induced by the tone generating resonant mechanisms. Stochastic analysis of the wavelet coefficient modulus of the surface pressure fluctuations was also carried out to demonstrate the inherent differences of different tonal frequencies. An understanding into the nature of the noise generated from the slat will help design the new generation of quite high-lift devices.
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Arif, Muhammad Irsalan, Randolph Chi Kin Leung, Garret Lam et Muhammad Rehan Naseer. « Fluid-Structure Interactions and Aeroacoustic coupling of Airfoil with Flexible Membrane(s) ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 265, no 3 (1 février 2023) : 4166–77. http://dx.doi.org/10.3397/in_2022_0594.
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In this paper, fluid-structure interactions of a NACA 0012 airfoil mounted with short flexible membrane(s) and its coupling effect on airfoil aeroacoustics are presented. A time-domain direct aeroacoustic simulation coupled with structural dynamics is carried out at a low Reynolds number of 50,000 to explore the aeroacoustic-structural interactions. Two different airfoil configurations based on single and dual membranes are analyzed. The membrane deflections and their impact on the flow field are characterized in wavenumber-frequency domain to analyze the structural dynamics due to flow unsteadiness within the laminar boundary layer and the resulting acoustic waves emanating from the airfoil trailing edge. A strong correlation between the membrane displacement and downstream propagating flow is observed for all configurations whereas the correlation is considerably weakened between the membrane displacement and upstream acoustic waves which ultimately results in the airfoil self-noise reduction without affecting the airfoil aerodynamics. The extent of noise reduction for dual membrane airfoil configuration is observed to be considerably higher than the single membrane airfoil configuration which corresponds to a much lower correlation among the upstream propagating acoustic waves and membrane deflection for both the membranes and redistribution of upstream flow energy into different frequencies.
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Bernardini, Giovanni, Francesco Centracchio, Massimo Gennaretti, Umberto Iemma, Claudio Pasquali, Caterina Poggi, Monica Rossetti et Jacopo Serafini. « Numerical Characterisation of the Aeroacoustic Signature of Propeller Arrays for Distributed Electric Propulsion ». Applied Sciences 10, no 8 (11 avril 2020) : 2643. http://dx.doi.org/10.3390/app10082643.
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This paper presents an investigation of the aerodynamic and aeroacoustic interaction of propellers for distributed electric propulsion applications. The rationale underlying the research is related to the key role that aeroacoustics plays in the establishment of the future commercial aviation scenario. The sustainable development of airborne transportation system is currently constrained by community noise, which limits the operations of existing airports and prevents the building of new ones. In addition, the substantial saturation of the existing noise abatement technologies inhibits the further development of the existing fleet, and imposes the adoption of disruptive configurations in terms of airframe layout and propulsion technology. Simulation-based data may help in clarifying many aspects related to the acoustic impact of such innovative concepts. Blended-wing-body equipped with distributed electric propulsion is one of the most promising, due to the beneficial effect of the substantial shielding induced by its geometry. Nevertheless, the novelty of the layout requires a thorough investigation of specific aspect for which no previous experience is available. Herein, the interaction between propellers is analysed for a fixed propeller geometry, as a function of their mutual distance and compared to the acoustic pattern of the isolated one. The aerodynamic results have been obtained using a boundary integral formulation for unsteady, incompressible, potential flows which accounts for the interaction between free wakes and propellers. For the aeroacoustic analyses, the Farassat 1A boundary integral formulation for the solution of the Ffowcs Williams and Hawkings equation has been used. These results provide an insight into the minimum distance between propellers to avoid aerodynamic/aeroacoustic interaction effects, which is an important starting point for the development of distributed propulsion systems.
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Arif, Irsalan, Randolph C. K. Leung et Muhammad Rehan Naseer. « A computational study of trailing edge noise suppression with embedded structural compliance ». JASA Express Letters 3, no 2 (février 2023) : 023602. http://dx.doi.org/10.1121/10.0017321.
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A unique concept for suppression of trailing edge noise scattering from a splitter plate in a low Reynolds number flow is proposed. The key idea of the concept is the adoption of a structural compliance system embedded with a finite number of elastic panels. Specific compliance system designs are devised for promotion of panel structural resonance that effectively absorbs broadband flow/acoustic fluctuation energy responsible for noise scattering. The concept is examined using high-fidelity direct aeroacoustic simulation together with spatiotemporal aeroacoustic-structural interaction analysis. The concept is confirmed feasible and outperforms many similar trailing edge noise reduction approaches reported in the literature.
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Zhao, Xin Yi, Ke Dong Zhou, Lei He, Ye Lu, Jia Wang et Qiu Zheng. « Numerical Simulation and Experiment on Impulse Noise in a Small Caliber Rifle with Muzzle Brake ». Shock and Vibration 2019 (9 septembre 2019) : 1–12. http://dx.doi.org/10.1155/2019/5938034.
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Blast waves generated from the muzzles of weapons may exert negative effects, such as shock waves and impulse noise. If the weapon is fired with a muzzle brake, these effects are recognized to be more severe. This paper discusses the influence of the muzzle brake on certain aeroacoustic noise characteristics based on numerical simulations and a corresponding experiment. The impulse noise, which is induced by complex jet flows discharging from small caliber rifles with muzzle brakes, is focused in this study. Computational fluid dynamics (CFD) and computational aeroacoustics (CAA) are combined to calculate the muzzle flow field and jet noise for cases with and without a muzzle brake, and then the data sets are carefully compared. The simulations indicate that the muzzle brake alters the muzzle flow field and directional distribution of the jet noise compared to a rifle sans muzzle brake. Deviations less than 7.6% between experimental data and simulation results validate the simulation model. The results presented in this paper may provide a workable reference for the prediction of muzzle noise and the optimization of muzzle brake designs.
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Liu, Zhen, Chen Bu, Xiangxu Kong, Dong Yang et Bingfei Li. « Computational investigation of noise interaction for a nano counter-rotating rotor in a static condition ». International Journal of Computational Materials Science and Engineering 07, no 01n02 (juin 2018) : 1850004. http://dx.doi.org/10.1142/s2047684118500045.
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The interaction between the upper and lower rotors greatly influences the aeroacoustic characteristics of a counter-rotating nano-coaxial rotor. To study this influence, a numerical investigation was carried out. The unsteady flow field of a single upper rotor was first studied with a large-eddy simulation computational fluid dynamics method coupled with a sliding-mesh technique. The Ffowcs Williams–Hawking equation method was used to investigate the aeroacoustic characteristics of the upper rotor based on the flow field. An experimental setup was established to validate the computational approach. The experimental results matched well with the computational results. Additionally, results show that the peak value of the total sound pressure level appeared near the blade tip, which verified that the tip vortex was one of the most important sources of rotor noise. Then the aeroacoustic noise of the nano-coaxial rotor was studied numerically. It was found that the total sound pressure level of the nano-coaxial rotor was greater than that of the upper rotor. Flow field analysis showed that the shedding vortices of the upper rotor interacted with the lower rotor, resulting in a blade–vortex interaction. It was evident that the aeroacoustic noise was enhanced by the interference between the upper and lower rotors.
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Chirico, G., G. N. Barakos et N. Bown. « Numerical aeroacoustic analysis of propeller designs ». Aeronautical Journal 122, no 1248 (29 novembre 2017) : 283–315. http://dx.doi.org/10.1017/aer.2017.123.
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ABSTRACTAs propeller-driven aircraft are the best choice for short/middle-haul flights but their acoustic emissions may require improvements to comply with future noise certification standards, this work aims to numerically evaluate the acoustics of different modern propeller designs. Overall sound pressure level and noise spectra of various blade geometries and hub configurations are compared on a surface representing the exterior fuselage of a typical large turboprop aircraft. Interior cabin noise is also evaluated using the transfer function of a Fokker 50 aircraft. A blade design operating at lower RPM and with the span-wise loading moved inboard is shown to be significantly quieter without severe performance penalties. The employed Computational Fluid Dynamics (CFD) method is able to reproduce the tonal content of all blades and its dependence on hub and blade design features.
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Oettle, Nicholas, et David Sims-Williams. « Automotive aeroacoustics : An overview ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 231, no 9 (10 avril 2017) : 1177–89. http://dx.doi.org/10.1177/0954407017695147.
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Vehicle aeroacoustic performance has a major influence on customer perception and also has importance for safety and comfort. Wind noise performance was once differentiated by the quality of sealing. Today, achieving competitive wind noise performance also depends on minimising aeroacoustic noise sources generated by the vehicle form, and on attenuation in the noise pathway from sources on the exterior to the vehicle interior. The reduction in noise transmission, especially through glazed surfaces, will continue to play an important role in controlling cabin noise, with a particular emphasis on achieving attenuation efficiently in terms of component mass. The human brain is not only sensitive towards the level of steady broadband noise, but distinctive features such as tonality or modulation draw the attention of the vehicle occupant and impact negatively on perception. Complex indices are often required to define good wind noise performance. This includes the consideration of multiple frequency bands and effects of the range of yaw angles experienced on-road. A key to achieving future vehicle refinement is bringing together an understanding of unsteady onset flow conditions, their impact on cabin sound pressure level and modulation and, in turn, the impact of noise level and modulation on psychoacoustic perception.
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Delbari, Seyed Hamid, Amir Nejat, Mohammad H. Ahmadi, Ali Khaleghi et Marjan Goodarzi. « Numerical modeling of aeroacoustic characteristics of different savonius blade profiles ». International Journal of Numerical Methods for Heat & ; Fluid Flow 30, no 6 (19 juin 2019) : 3349–69. http://dx.doi.org/10.1108/hff-12-2018-0764.
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Purpose This study aims to carry out numerical modeling to predict aerodynamic noise radiation from four different Savonius rotor blade profile. Design/methodology/approach Incompressible unsteady reynolds-averaged navier-stokes (URANS) approach using gamma–theta turbulence model is conducted to obtain the time accurate turbulent flow field. The Ffowcs Williams and Hawkings (FW-H) acoustic analogy formulation is used for noise predictions at optimal tip speed ratio (TSR). Findings The mean torque and power coefficients are compared with the experimental data and acceptable agreement is observed. The total and Mono+Dipole noise graphs are presented. A discrete tonal component at low frequencies in all graphs is attributed to the blade passing frequency at the given TSR. According to the noise prediction results, Bach type rotor has the lowest level of noise emission. The effect of TSR on the noise level from the Bach rotor is investigated. A direct relation between angular velocity and the noise emission is found. Practical implications The savonius rotor is a type of vertical axis wind turbines suited for mounting in the vicinity of residential areas. Also, wind turbines wherein operation are efficient sources of tonal and broadband noises and affect the inhabitable environment adversely. Therefore, the acoustic pollution assessment is essential for the installation of wind turbines in residential areas. Originality/value This study aims to investigate the radiated noise level of four common Savonius rotor blade profiles, namely, Bach type, Benesh type, semi-elliptic and conventional. As stated above, numbers of studies exploit the URANS method coupled with the FW-H analogy to predict the aeroacoustics behavior of wind turbines. Therefore, this approach is chosen in this research to deal with the aeroacoustics and aerodynamic calculation of the flow field around the aforementioned Savonius blade profiles. The effect of optimal TSR on the emitted noise and the contribution of thickness, loading and quadrupole sources are of interest in this study.
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Guo, Jingwen, Xiangtian Li, Chenyu Ren et Xin Zhang. « Recognizing the aeroacoustic information of noise radiated by an unflanged duct based on convolutional neural networks ». Journal of the Acoustical Society of America 152, no 5 (novembre 2022) : 2531–42. http://dx.doi.org/10.1121/10.0015003.
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Accurately recognizing the aeroacoustic information of noise propagating into and radiating out of an aero-engine duct is of both fundamental and practical interest. The aeroacoustic information includes (1) the acoustic properties of the noise source, such as the frequency ( f) and the circumferential and radial mode numbers ( m, n), and (2) the flight conditions, including the ambient flow speed ( M0) and the jet flow speed ( M1). In this study, a data-driven model is developed to predict the aeroacoustic information of a simplified aero-engine duct noise from the far-field sound pressure level directivity. The model is constructed by the integration of one-dimensional convolutional layers and fully connected layers. The training and validation datasets are calculated from the analytical model for noise radiation from a semi-infinite unflanged duct based on the Wiener–Hopf method. For a single-spinning mode source, a regression model is established for f, M0, and M1 prediction, and a classification model is built up for m and n prediction. Additionally, for a multi-spinning mode source, the regression model is used to predict the coefficient of each mode. Results show that the proposed data-driven model can effectively and robustly predict the acoustic characteristics of noise propagation in and radiation out of an aero-engine bypass duct.
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Mao, Meiliang, Yi Jiang, Xiaogang Deng et Huayong Liu. « Noise Prediction in Subsonic Flow Using Seventh-Order Dissipative Compact Scheme on Curvilinear Mesh ». Advances in Applied Mathematics and Mechanics 8, no 2 (27 janvier 2016) : 236–56. http://dx.doi.org/10.4208/aamm.2014.m459.
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AbstractIn this paper, we investigate the performance of the seventh-order hybrid cell-edge and cell-node dissipative compact scheme (HDCS-E8T7) on curvilinear mesh for noise prediction in subsonic flow. In order to eliminate the errors due to surface conservation law (SCL) is dissatisfied on curvilinear meshes, the symmetrical conservative metric method (SCMM) is adopted to calculate the grid metric derivatives for the HDCS-E8T7. For the simulation of turbulence flow which may have main responsibility for the noise radiation, the new high-order implicit large eddy simulation (HILES) based on the HDCS-E8T7 is employed. Three typical cases, i.e., scattering of acoustic waves by multiple cylinder, sound radiated from a rod-airfoil and subsonic jet noise from nozzle, are chosen to investigate the performance of the new scheme for predicting aeroacoustic problem. The results of scattering of acoustic waves by multiple cylinder indicate that the HDCS-E8T7 satisfying the SCL has high resolution for the aeroacoustic prediction. The potential of the HDCS-E8T7 for aeroacoustic problems on complex geometry is shown by the predicting sound radiated from a rod-airfoil configuration. Moreover, the subsonic jet noise from nozzle has been successfully predicted by the HDCS-E8T7.
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Tabata, Ryoya, Katsuya Uchida, Yuko Okada, Yoshikazu Honji et Kin'ya Takahashi. « Aeroacoustic analysis of a bass-reflex loudspeaker using LES : Validation of 2D and 3D numerical model with experiment ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, no 7 (30 novembre 2023) : 1024–34. http://dx.doi.org/10.3397/in_2023_0158.
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A bass-reflex loudspeaker has a port that amplifies low frequencies through Helmholtz resonance. However, high sound pressure levels can cause fluid flow near the port tip, leading to noise and distortion. Two-dimensional axisymmetric aeroacoustic analysis is commonly used to predict these non-linear phenomena; however, it has been reported to overestimate harmonic distortion. Presently, its accuracy has not been adequately verified through three-dimensional simulations or comparison with experimental results. This study validates the numerical model by comparing results from three- and two-dimensional analyses with experimental measurements on a straight tube port axisymmetric speaker model. In aeroacoustic analysis, large-eddy simulations are adopted, and the speaker model is acoustically driven at the Helmholtz resonance frequency. The results show that while the two-dimensional axisymmetric model overestimates the harmonic distortion and noise in the frequency response of far-field sound pressure, the three-dimensional model agrees well with the experiment up to the band where the harmonic distortion and port noise appear. This indicates that three-dimensional aeroacoustic analysis is necessary to accurately reproduce the fluid-induced distortion and noise of a bass-reflex port speaker.
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Fu, Jinbin, et Luigi Vigevano. « Aeroacoustic modeling of helicopter transonic rotor noise ». Aerospace Science and Technology 122 (mars 2022) : 107430. http://dx.doi.org/10.1016/j.ast.2022.107430.
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ITOH, Atsushi, Yasuhiko OKUTSU, Naoki HAMAMOTO et ZongGuang WANG. « Aeroacoustic Noise Simulation of a Simple Duct ». Proceedings of the Fluids engineering conference 2019 (2019) : IS—02. http://dx.doi.org/10.1299/jsmefed.2019.is-02.
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Washburn, Karl, Christopher Peak et Robert Sandboge. « Computational aeroacoustic modeling of rotary mower noise ». Journal of the Acoustical Society of America 122, no 5 (2007) : 2963. http://dx.doi.org/10.1121/1.2942560.
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Ewert, R., J. Dierke, A. Neifeld, C. Appel, M. Siefert et O. Kornow. « CAA broadband noise prediction for aeroacoustic design ». Procedia Engineering 6 (2010) : 254–63. http://dx.doi.org/10.1016/j.proeng.2010.09.027.
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Ewert, R., J. Dierke, J. Siebert, A. Neifeld, C. Appel, M. Siefert et O. Kornow. « CAA broadband noise prediction for aeroacoustic design ». Journal of Sound and Vibration 330, no 17 (août 2011) : 4139–60. http://dx.doi.org/10.1016/j.jsv.2011.04.014.
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Li, Dichen, et Chuang Wei. « Numerical Study on Aerodynamic and Aeroacoustic Performances of Bioinspired Wings ». Applied Bionics and Biomechanics 2023 (17 novembre 2023) : 1–16. http://dx.doi.org/10.1155/2023/9930841.
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Noise control has become one of the key issues to be considered in modern aeronautical machinery design. Many efforts have been devoted to noise reduction of airfoils and wings, including traditional flow control methods. In fact, some animals in wild nature exhibit superior aerodynamic and aeroacoustic performance, providing novel ideas for solving this engineering problem. In this research, bionic technology is used to obtain quiet and efficient wing. Inspired by the owl’s wing, we propose two bionic configurations, one coupled with leading edge waves and trailing edge serrations. The Large Eddy Simulation and the Ffowcs-Williams and Hawkings equation is applied to simulate the aerodynamic and aeroacoustic characteristics of wings at low-Reynolds number flow. Numerical results demonstrate that the bioinspired wings have excellent aerodynamic performances and remarkable lower overall sound pressure level compared to NACA 0016 which has similar relative thickness. In addition, the unsmooth structure of leading edge waves and trailing edge serrations provide an additional 4.27 dB noise suppression effect, with little impact on aerodynamic characteristics at small angle of attack. The detailed analysis reveals that, due to the special owl-based profile, the flow around two bioinspired wings is mainly turbulent on the upper and lower surfaces, and no laminar separation bubble is detected at the trailing edge. Moreover, the unsmooth structure modifications successfully weaken the scale and scope of coherent vortex structures. These factors contribute to reducing the associated pressure fluctuation, thereby controlling the aeroacoustic noise of wing. Consequently, a coupled bionic wing is presented with the excellent aerodynamic and aeroacoustic characteristics. The conclusions are envisioned to be beneficial to the design of new generation low-noise aeronautical machinery.
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Long, Shuang Li, Hong Nie et Xin Xu. « Aeroacoustic Study on a Simplified Nose Landing Gear ». Applied Mechanics and Materials 184-185 (juin 2012) : 18–23. http://dx.doi.org/10.4028/www.scientific.net/amm.184-185.18.
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Simulation analysis and experiment research are performed on the aeroacoustic noise of a landing gear component in this paper. Detached Eddy Simulation (DES) is used to produce the flow field of the model. The Ffowcs-Williams/Hawkings (FW-H) equation is used to calculate the acoustic field. The sound field radiated from the model is measured in the acoustic wind tunnel. A comparison shows that the simulation results agree well with the experiment results under the acoustic far field condition. The results show that the noise radiated from the model is broadband noise. The directivity of the noise source is like a type of dipole. The wheel is the largest contributor and the strut is the least contributor to the landing gear noise. The results can provide some reference for low noise landing gear design.
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ARIF, Irsalan, Randolph C. K. LEUNG, Muhammad Rehan NASEER et Shuaib SALAMAT. « Reduction of Flow-Induced Trailing Edge Noise of Semi-Infinite Flat Plate by Structural Resonance ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, no 3 (30 novembre 2023) : 5302–10. http://dx.doi.org/10.3397/in_2023_0747.
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A unique method for the reduction in flow-induced trailing edge noise scattering for a semi-infinite thin plate is proposed by utilizing short flexible panels mounted on the surface of the plate. The proposed configuration differs from conventional cantilevered elastic trailing edges due to the limitations of their structural integrity and applicability. The key idea is to design short panels that vibrate in structural resonance under the fluid loading for absorbing the energy from the flow to sustain their vibration. A time-domain direct aeroacoustic simulation coupled with structural dynamics is carried out at a low Reynolds number of 50,000 to explore the aeroacoustic-structural interactions. The effectiveness of noise reduction of the designed configuration is analyzed by comprehensive aeroacoustic analysis where a significant noise reduction is observed for the plate mounted with three flexible panels without any adverse effects on the plate aerodynamics. The structural analysis shows a systematic vibration pattern for all the panels which clearly indicates the presence of complex fluid-structural interaction under resonance conditions. Design strategy of the proposed configuration along with its limitations are also discussed.
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NASEER, Muhammad Rehan, Irsalan ARIF et Randolph C. K. LEUNG. « Utilization of Embedded Surface Compliance for Suppression of Deep Cavity Flow Noise ». INTER-NOISE and NOISE-CON Congress and Conference Proceedings 268, no 3 (30 novembre 2023) : 5323–34. http://dx.doi.org/10.3397/in_2023_0750.
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Cavity noise suppression is one of the extensively debated aeroacoustic research problem due to its application over the wide range of mechanical systems. This study presents a scheme of embedding surface compliance in form of elastic panels on cavity walls as a mean to achieve significant tonal noise reduction. A deep cavity of aspect ratio D/L = 0.4 operating at Mach number 0.09 is considered. Using the Direct Aeroacoustic Simulation, the rigid cavity case is investigated to uncover the underlying physical processes driving the aeroacoustic coupling phenomenon between the shear layer and the cavity mode. The analysis suggests that each cavity wall supports a certain coupling-associated activity and therefore provides a platform to modify the shear layer - cavity mode interaction in a tacit way through the well-designed positioning of elastic panels. The accordantly mounted elastic panels are then excited with the flow perturbation energy to significantly reduce the pressure fluctuations magnitude of the cavity mode which strongly affects its synchronization with shear layer and hence presents the possibility of significant noise reduction.
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Klimczyk, Witold, et Adam Sieradzki. « Airofil Tonal Noise Prediction Using Urans ». Transactions on Aerospace Research 2023, no 4 (1 décembre 2023) : 1–17. http://dx.doi.org/10.2478/tar-2023-0019.
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Abstract To examine the feasibility of the laminar boundary layer (LBL), vortex shedding (VS) tonal noise modelling using unsteady Reynolds-averaged Navier–Stokes (URANS) was investigated for the non-symmetric S834 airfoil. A transition SST turbulence model was used to model the laminar-turbulent transition and its vital influence on the laminar bubble and hydrodynamic instabilities generation. The influence of turbulence on the unsteady vortex patterns was investigated. Hence, the hybrid aeroacoustic analysis with Lighthill analogy was conducted to obtain the acoustic pressure field. The approach allowed us to model hydrodynamic instabilities and the resulting VS tonal noise. The frequency of VS matched the experimental data, giving the same 1/3 octave tonal peak only for a limited freestream turbulence regime. The simplification of the present method did not allow us to model the aeroacoustic feedback loop, and resulted in lack of instabilities for higher freestream turbulence.
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Deparday, J., H. Müller, T. Polonelli et S. Barber. « An experimental system to acquire aeroacoustic properties on wind turbine blades ». Journal of Physics : Conference Series 2265, no 2 (1 mai 2022) : 022089. http://dx.doi.org/10.1088/1742-6596/2265/2/022089.
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Abstract Wind turbine noise is a key issue preventing the successful exploitation of the full potential of wind energy throughout the world, especially in urban areas. To better assess and predict wind turbine noise, several aeroacoustic simulations and models have been developed over the past. Many semi-empirical models for noise emission and propagation rely on aeroacoustic properties at the blade level, including the pressure gradient, the spectrum of the pressure fluctuations, the convection velocity and the coherence lengths. Field measurements of these local quantities on operating wind turbines are valuable to improve the accuracy of the models. In the Aerosense project, a cost-effective smart measurement system is being developed that is thin, easy to install without damaging the blade, low power, self-sustaining and wirelessly transmitting. This measurement system uses MEMS sensors, which require some calibrations and corrections to obtain sufficiently accurate data. This paper describes the experimental system and its workflow, which has been developed within the Aerosense project to obtain sufficiently accurate measurements for semi-empirical noise emission and propagation models. The experimental system and its workflow are then validated in an anechoic wind tunnel on a NACA63-418 airfoil. The results show that this experimental system is able to acquire relevant aeroacoustic properties on operating wind turbines.
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Kang, Qiang, Shuguang Zuo et Kaijun Wei. « Study on the aerodynamic noise of internal flow of regenerative flow compressors for a fuel-cell car ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 228, no 7 (30 août 2013) : 1155–74. http://dx.doi.org/10.1177/0954406213500746.
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The regenerative flow compressor used in fuel-cell cars generates high aerodynamic noise, which is the main source of noise. Compared with the research on centrifugal or axial turbomachinery, research on the noise of regenerative flow compressors is far from adequate. This paper presents the on-going work on it at Tongji University based on both experimental and computational works. In this study, a three-dimensional unsteady computational fluid dynamic model of the compressor was constructed with the large eddy approach. The pressure fluctuation, vortex noise source and Ffowcs William-Hawkings (FW-H) method were used to analyze the characteristics of the aerodynamic noise sources. Additionally, the far-field aerodynamic noise generated by the internal flow of the compressor was predicted using the aeroacoustic finite element method. The simulation results were validated with the experimental data. It was found that combining the fluid dynamic model and aeroacoustic finite element analysis promising results for aerodynamic noise prediction of compressors could be produced. The effects of the impeller parameters on the aerodynamic noise of the compressor were also studied.
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Kan, Zi, Daochun Li, Shiwei Zhao, Jinwu Xiang et Enlai Sha. « Aeroacoustic and aerodynamic characteristics of a morphing airfoil ». Aircraft Engineering and Aerospace Technology 93, no 5 (1 juillet 2021) : 888–99. http://dx.doi.org/10.1108/aeat-11-2020-0263.
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Purpose This paper aims to assess the aeroacoustic and aerodynamic performance of a morphing airfoil with a flexible trailing edge (FTE). The objective is to make a comparison of the aerodynamic noise characteristics between the conventional airfoil with a flap and morphing airfoil and analyse the noise reduction mechanisms of the morphing airfoil. Design/methodology/approach The computational fluid dynamic method was used to calculate the aerodynamic coefficients of morphing airfoil and the Ffowcs-Williams and Hawking’s acoustic analogy methods were performed to predict the far-field noise of different airfoils. Findings Results show that compared with the conventional airfoil, the morphing airfoil can generate higher lift and lower noise, but a greater drag. Additionally, the noise caused by the one-unit lift of the morphing airfoil is significantly lower than that of the conventional airfoil. For the morphing airfoil, the shedding vortex in the trailing edge was the main noise resource. As the angle of attack (AoA) increases, the overall sound pressure level of the morphing airfoil increases significantly. With the increase of the trailing edge deflection angle, the amplitude and the period of sound pressure of the morning airfoil fluctuation increase. Practical implications Presented results could be very useful during designing the morphing airfoil with FTE, which has significant advantages in aerodynamic efficiency and aeroacoustic performance. Originality/value This paper presents the aerodynamic and aeroacoustic characteristics of the morphing airfoil. The effect of trailing edge deflection angle and AoA on morphing airfoil was investigated. In the future, using a morphing airfoil instead of a traditional flap can reduce the aircraft`s fuel consumption and noise pollution.
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Bernardi, Claudio, Federico Porcacchia, Claudio Testa, Pietro De Palma, Stefano Leonardi et Stefania Cherubini. « NREL-5MW Wind Turbine Noise Prediction by FWH-LES ». International Journal of Turbomachinery, Propulsion and Power 8, no 4 (6 décembre 2023) : 54. http://dx.doi.org/10.3390/ijtpp8040054.
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This paper deals with large onshore wind turbine aeroacoustics. Noise from the NREL 5 MW device is predicted by the permeable-surface Ffowcs Williams–Hawkings equation (FWH-P), starting from the postprocessing of LES data on different acoustic surfaces S. Their size and placement is aimed at embedding most of the aerodynamic sources of sound surrounding rotor and nacelle. Due to the presence of eddies that inevitably cross S, this paper compares results from open and closed acoustic surfaces, and the outflow disk averaging technique. The issues related to the interpolation process of LES data on S is discussed as well. In order to assess the LES/FWH-P aeroacoustic platform, LES and FWH-P pressures are compared in the very-near field. It is shown that, within the limits of the discretization settings imposed by the interpolation procedure and for the Reynolds number working condition investigated herein, the lack of quadrupole sources outside the permeable surface(s) deeply affect the quality of FWH-P acoustic pressures with respect to direct LES signals.
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Mendoza, J. M., T. F. Brooks et W. M. Humphreys. « An Aeroacoustic Study of a Leading EDGE Slat Configuration ». International Journal of Aeroacoustics 1, no 3 (septembre 2002) : 241–74. http://dx.doi.org/10.1260/147547202320962583.
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Aeroacoustic evaluations of high-lift devices have been carried out in the Quiet Flow Facility of the NASA Langley Research Center. The present paper describes detailed flow and acoustic measurements that have been made in order to better understand the noise generated from airflow over a wing leading edge slat configuration, and to possibly predict and reduce this noise source. The acoustic database is obtained by a moveable Small Aperture Directional Array of microphones designed to electronically steer to different portions of models under study. The slat is shown to be a uniform distributed noise source. The data was processed such that spectra and directivity were determined with respect to a one-foot span of slat. The spectra are normalized in various fashions to demonstrate slat noise character. In order to equate portions of the spectra to different slat noise components, trailing edge noise predictions using measured slat boundary layer parameters as inputs are compared to the measured slat noise spectra.