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Journal articles on the topic 'Aerodynamic and acoustic data'

Author: Grafiati

Published: 4 June 2021

Last updated: 1 February 2022

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1

Mahdal, Miroslav, Josef Dobeš, and Milada Kozubková. "Measurement of Aerodynamic and Acoustic Quantities Describing Flow around a Body Placed in a Wind Tunnel." Measurement Science Review 19, no. 1 (2019): 20–28. http://dx.doi.org/10.2478/msr-2019-0004.

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Abstract Aerodynamically generated noise affects passenger comfort in cars, high-speed trains, and airplanes, and thus, automobile manufacturers aim for its reduction. Investigation methods of noise and vibration sources can be divided into two groups, i.e. experimental research and mathematical research. Recently, owing to the increase in computing power, research in aerodynamically generated noise (aero-acoustics) is beginning to use modern methods such as computational fluid dynamics or fluid-structure interaction. The mathematical model of turbulent flow is given by the system of partial d

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2

Patel, Rita R., Shaheen N. Awan, Julie Barkmeier-Kraemer, et al. "Recommended Protocols for Instrumental Assessment of Voice: American Speech-Language-Hearing Association Expert Panel to Develop a Protocol for Instrumental Assessment of Vocal Function." American Journal of Speech-Language Pathology 27, no. 3 (2018): 887–905. http://dx.doi.org/10.1044/2018_ajslp-17-0009.

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Purpose The aim of this study was to recommend protocols for instrumental assessment of voice production in the areas of laryngeal endoscopic imaging, acoustic analyses, and aerodynamic procedures, which will (a) improve the evidence for voice assessment measures, (b) enable valid comparisons of assessment results within and across clients and facilities, and (c) facilitate the evaluation of treatment efficacy. Method Existing evidence was combined with expert consensus in areas with a lack of evidence. In addition, a survey of clinicians and a peer review of an initial version of the protocol

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Guérin, S., R. Schnell, and R. G. Becker. "Performance prediction and progress towards multi-disciplinary design of contra-rotating open rotors." Aeronautical Journal 118, no. 1208 (2014): 1159–79. http://dx.doi.org/10.1017/s0001924000009830.

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Abstract At DLR’s Institute of Propulsion Technology, the prediction tools and multi-disciplinary optimisation strategies developed for turbofan engines have been extended to contra-rotating open rotors (CROR). Thereby the objective has been to appraise and improve the performance of CROR engines and thus to reduce their environmental impact. The present paper reviews the intermediate progress achieved in this scope. The prediction is based on analytical and CFD methods and covers the fields of engine performance analysis, aerodynamics and acoustics. The aerodynamic and acoustic results could

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Zheng, Zhengyu. "Prediction of dipole sources and aeroacoustics field for tandem cylinder flow field based on DBEM/hybrid LES." International Journal of Aeroacoustics 20, no. 1-2 (2021): 157–73. http://dx.doi.org/10.1177/1475472x20984092.

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In this paper, the DBEM/Hybrid LES（Directly Boundary Element Method/Hybrid Large Eddy Simulation）technique is applied to predict the aerodynamic noise generated by tandem circular cylinders immersed in a three-dimensional turbulent flow. Utilizing the Lighthill's Acoustic Analogy, the flow pressure fluctuation near the surface of the cylinder is converted into acoustic dipole sources. Taking the dipole sound sources as the actual sound sources, the aeroacoustic field is simulated and analyzed by DBEM. The research shows that: The strong dipole sources are distributed in the collision zone of t

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Buffum, D. H., and S. Fleeter. "Effect of Wind Tunnel Acoustic Modes on Linear Oscillating Cascade Aerodynamics." Journal of Turbomachinery 116, no. 3 (1994): 513–24. http://dx.doi.org/10.1115/1.2929440.

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The aerodynamics of a biconvex airfoil cascade oscillating in torsion is investigated using the unsteady aerodynamic influence coefficient technique. For subsonic flow and reduced frequencies as large as 0.9, airfoil surface unsteady pressures resulting from oscillation of one of the airfoils are measured using flush-mounted high-frequency-response pressure transducers. The influence coefficient data are examined in detail and then used to predict the unsteady aerodynamics of a cascade oscillating at various interblade phase angles. These results are correlated with experimental data obtained

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Andreassen, Meri L., Herbert A. Leeper, Duncan L. Macrae, and Ian R. Nicholson. "Aerodynamic, Acoustic, and Perceptual Changes following Adenoidectomy." Cleft Palate-Craniofacial Journal 31, no. 4 (1994): 263–70. http://dx.doi.org/10.1597/1545-1569_1994_031_0263_aaapcf_2.3.co_2.

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Fourteen children were seen prior to adenoidectomy and at 1 month, 3 months, and 6 months following surgery. On each visit, nasal airway resistance values, nasal cross-sectional area estimates, nasalance scores, and perceptual ratings of nasality were collected. These data were analyzed to identify changes that were related to the time of the test, and to the primary indication for surgery (nasal airway obstruction or recurrent infection). Results revealed significant reduction in nasal airway resistance and significant changes in nasalance following surgery. Perceptual changes were not signif

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Cican, Grigore, and Daniel Eugeniu Crunteanu. "Aerodynamic Noise Control Study of Nozzles with Triangular Chevrons." Applied Mechanics and Materials 436 (October 2013): 25–31. http://dx.doi.org/10.4028/www.scientific.net/amm.436.25.

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This paper has a small part of notion of chevron and the process that helps reducing the noise pollution. Based on the gas dynamic and geometrical parameters of a single flow jet engine one does a model of CFD data processing. In this process one observes the influence of chevrons on acoustic wave intensity produced by the jet . One studies a series of tests on triangular chevrons: immersions, the influence of the number of chevrons in order to settle the influence of the geometrical parameters on the flow and on the jet acoustics. Finally one presents the contribution of chevrons in noise pol

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Fan, Feng, Yaxiong Cao, Lusheng Jiang, and Yongfeng Lin. "Research on Calculation Method for Acoustic Scattering of Helicopter Noise." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 38, no. 6 (2020): 1275–83. http://dx.doi.org/10.1051/jnwpu/20203861275.

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A new calculation method of helicopter rotor/fuselage acoustic scattering is developed. Firstly, a CFD analysis model is developed to simulate flow field of the rotor, which is based on the motional embedded grid system and RANS equations, and provides aerodynamic data for rotor noise calculation. Then, FW-H equations are employed to calculate the aeroacoustic characteristics of isolated rotor, and G 1A formulas are applied to calculate the rotor acoustic gradient to provide boundary condition for acoustic scattering. Based on these, the time-domain equivalent source method is applied to calcu

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MacEachern, Margaret R. "Computer modeling of the production of ejectives using aerodynamic and acoustic data." Journal of the Acoustical Society of America 100, no. 4 (1996): 2661. http://dx.doi.org/10.1121/1.417461.

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10

Shendge, Smit. "Study and Design Frontal Area of a Car to Curtail Aerodynamic Noise." International Journal for Research in Applied Science and Engineering Technology 9, no. 8 (2021): 1637–52. http://dx.doi.org/10.22214/ijraset.2021.37640.

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Abstract: In this field of comparative research study, comparison of two car model, a standard car and an optimized car with respect to aerodynamic analysis/aeroacoustics analysis with the help of CFD software Ansys 2019 R2 version is taken in consideration to compare the results and get to know if the optimized car model has reduction in the generation of aerodynamic noise when it travels at four different speeds (30 m/s, 40 m/s, 50m/s and 60m/s). For carried out aeroacoustics/aerodynamic noise analysis two main model are used turbulence model and an acoustics model. For turbulence model and

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Liu, FeiFei, ShuJie Jiang, Gang Chen, and Yueming Li. "Numerical Investigation on Vortex-Structure Interaction Generating Aerodynamic Noises for Rod-Airfoil Models." Mathematical Problems in Engineering 2017 (2017): 1–12. http://dx.doi.org/10.1155/2017/3704324.

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In past several decades, vortex-structure interaction generated aerodynamic noise became one of the main concerns in aircraft design. In order to understand the mechanism, the acoustic analogy method combined with the RANS-based nonlinear acoustics solver (NLAS) is investigated. The numerical method is firstly evaluated by the experiment data of the classic rod-airfoil model. Compared with the traditional analogy methods, the RANS/NLAS can capture the nonlinear aerodynamic noise more accurately with lower gird requirements. Then different rod-airfoil configurations were simulated to investigat

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Celebi, S., K. Yelken, O. N. Develioglu, et al. "Acoustic, perceptual and aerodynamic voice evaluation in an obese population." Journal of Laryngology & Otology 127, no. 10 (2013): 987–90. http://dx.doi.org/10.1017/s0022215113001916.

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AbstractObjective:To investigate perceptual, acoustic and aerodynamic voice parameters in obese individuals.Methods:Twenty obese and 20 normal-weight volunteers underwent voice evaluation by laryngoscopy, acoustic analysis, aerodynamic measurement and perceptual analysis (using the grade-roughness-breathiness-asthenia-strain (‘GRBAS') scale and the Voice Handicap Index 10 scale). Data from both subject groups were compared.Results:No difference was found in acoustic analysis parameters between the two groups (p > 0.05). Maximum phonation time in the obese group (mean ± standard deviation, 1

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Hu, Binfei, Zengjun Lu, Qiming Cui, Rongjiang Tang, Zhe Feng, and Daokun Bi. "Prediction and Aerodynamic Analysis of Interior Noise and Wind Drag Generated by the Outside Rear-View Mirror for Commercial Vehicles." Shock and Vibration 2020 (September 14, 2020): 1–16. http://dx.doi.org/10.1155/2020/8893959.

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The outside rear-view mirror (OSRVM) is installed on the vehicle’s surface, which causes unwanted aerodynamic noise and wind drag during driving. It is important to use simulation methods to predict the performance of aerodynamic noise and wind drag of commercial vehicles due to the OSRVM. Considering the wind drag of the OSRVM, a combinational simulation strategy is employed to calculate external flow and interior acoustic fields of commercial vehicles, respectively. The flow field is computed a priori with an incompressible flow solver. The acoustic field was then computed based on the infor

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Zuo, Shuguang, Chaofeng Xie, Xudong Wu, Yuejiao Li, and Kaijun Wei. "Numerical simulation and optimization of aerodynamic noise for claw pole alternator." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 233, no. 3 (2018): 857–79. http://dx.doi.org/10.1177/0954406218766191.

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This study aims at minimizing the aerodynamic noise generated by claw pole alternator used in vehicles. In this paper, an effective and efficient hybrid test-analysis engineering approach has been proposed to predict and optimize acoustic performance of claw pole alternator. First, an experimental analysis was performed to predict the main components of the aerodynamic noise generated by the claw pole alternator. Then a hybrid approach was proposed to calculate the aerodynamic noise of the alternator. A computational fluid dynamics model of the claw pole alternator was developed for calculatin

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Lee, Min Rae, and Joon Hyun Lee. "A Study on Characteristics of Leak Signals of Pipeline Using Acoustic Emission Technique." Solid State Phenomena 110 (March 2006): 79–88. http://dx.doi.org/10.4028/www.scientific.net/ssp.110.79.

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This study presents an approach to leak detection of pipeline review in terms of theoretical analysis such as acoustics and hydromechanics that should be accompanied by explanation of leakage. The acoustic emission signals during leak from circular hole of different geometries were studied both analytically and experimentally. The relationships between acoustic parameters and fluid mechanical parameters also were derived analytically. A quadrupole aerodynamic model was applied for the analysis of leak from the circular hole. Computer simulation results demonstrate the effectiveness of the prop

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Taratorin, Andrey, and Ainur Mukhametov. "OPTIMIZATION OF COMPLEXLY SHAPED DISSIPATIVE SILENCERS." VOLUME 39, VOLUME 39 (2021): 94. http://dx.doi.org/10.36336/akustika20213994.

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The article is about a comprehensive study of dissipative silencers of complex shapes. Analyzed the acoustic efficiency of such silencers. The sound absorption coefficient determined from experimental data. The acoustic properties of plate silencers take into account that coefficient. Presented the results of verification of models with plates of constant thickness. Considered the plates of complex shapes: uniform thickness change, convex and concave. Obtained results of modeling the acoustic efficiency of silencers with complex shape plates. These results are for different values of the mean

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STRAWN, ROGER C., RUPAK BISWAS, and ANASTASIOS S. LYRINTZIS. "HELICOPTER NOISE PREDICTIONS USING KIRCHHOFF METHODS." Journal of Computational Acoustics 04, no. 03 (1996): 321–39. http://dx.doi.org/10.1142/s0218396x96000106.

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This paper presents two methods for predicting the noise from helicopter rotors in forward flight. Aerodynamic and acoustic solutions in the near field are computed with a finite-difference solver for the Euler equations. Two different Kirchhoff acoustics methods are then used to propagate the acoustic signals to the far field in a computationally-efficient manner. One of the methods uses a Kirchhoff surface that rotates with the rotor blades. The other uses a nonrotating Kirchhoff surface. Results from both methods are compared to experimental data for both high-speed impulsive noise and blad

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Cox, Steven R., Stephanie Milillo, and Zahra Sedighi Maman. "Voice Characteristics of Female College Athletes: A Pilot Study." Perspectives of the ASHA Special Interest Groups 5, no. 1 (2020): 113–18. http://dx.doi.org/10.1044/2019_persp-19-00142.

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Purpose The purpose of this study was to identify changes in NCAA Division II female athletes' objective and subjective voice characteristics before, during, and after a regular volleyball season. Method Acoustic, aerodynamic, and Voice Handicap Index-10 data were collected from five female volleyball athletes at three timepoints: preseason, midseason, and postseason. Results Individual data suggest increases in objective and subjective voice characteristics at midseason, but many values returned to typical limits at postseason. Increases observed in acoustic, aerodynamic, and Voice Handicap I

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Moon, Jerald B., and Bernd Weinberg. "Aerodynamic and Myoelastic Contributions to Tracheoesophageal Voice Production." Journal of Speech, Language, and Hearing Research 30, no. 3 (1987): 387–95. http://dx.doi.org/10.1044/jshr.3003.387.

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Five laryngectomized, tracheoesophageal (TE) speakers completed a series of phonatory tasks developed to assess (a) aerodynamic and acoustic properties of TE voice and (b) aerodynamic and myoelastic contributions to the mediation of fundamental frequency change. These TE speakers' voices were characterized by increased trans-source airflow rates, comparable source driving pressures, and decreased airway resistances in comparison with standard esophageal speakers. TE speakers were capable of adjusting their voicing sources on a myoelastic basis to influence F o change. This result, coupled with

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Assoum, Hassan Hasan, Jana Hamdi, Mouhammad El Hassan, et al. "Turbulent kinetic energy and self-sustaining tones: Experimental study of a rectangular impinging jet using high Speed 3D tomographic Particle Image Velocimetry." Journal of Mechanical Engineering and Sciences 14, no. 1 (2020): 6322–33. http://dx.doi.org/10.15282/jmes.14.1.2020.10.0495.

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Impinging jets are widely used in ventilation systems to improve the mixing and diffusion of airflows. When a rectangular jet hits a slotted plate, an acoustic disturbance can be generated and self-sustained tones produced. Few studies have looked at the Turbulent Kinetic Energy (TKE) produced by the aerodynamic field in such configurations and in the presence of self-sustaining tones. The aim of this work is to investigate the energy transfer between the aerodynamic and acoustic fields generated in a rectangular jet impinging on a slotted plate. The present paper methodology is based on exper

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Nitzsche, F., and D. G. Opoku. "Acoustic validation of a new code using particle wake aerodynamics and geometrically-exact beam structural dynamics." Aeronautical Journal 109, no. 1096 (2005): 257–67. http://dx.doi.org/10.1017/s0001924000000713.

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Abstract This paper describes the validation of a new code for prediction both aeroacoustic and aeroelastic behaviour of hingeless rotors. The structural component is based on a non-linear beam element model considering small strains and finite rotations, which uses a mixed variational intrinsic formulation. The aerodynamic component is built on a loworder panel method incorporating a vortex particle free-wake model. The aerodynamic and structural components are combined to form a closely coupled aeroelastic code that solves in the time-domain. The loading and thickness noise terms for the aer

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Boudet, Jérôme, Nathalie Grosjean, and Marc C. Jacob. "Wake-Airfoil Interaction as Broadband Noise Source: A Large-Eddy Simulation Study." International Journal of Aeroacoustics 4, no. 1-2 (2005): 93–115. http://dx.doi.org/10.1260/1475472053730093.

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A large-eddy simulation is carried out on a rod-airfoil configuration and compared to an accompanying experiment as well as to a RANS computation. A NACA0012 airfoil (chord c = 0.1 m) is located one chord downstream of a circular rod (diameter d = c/10, Red = 48 000). The computed interaction of the resulting sub-critical vortex street with the airfoil is assessed using averaged quantities, aerodynamic spectra and proper orthogonal decomposition (POD) of the instantaneous flow fields. Snapshots of the flow field are compared to particle image velocimetry (PIV) data. The acoustic far field is p

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Tang, Hui, Yulong Lei, and Xingzhong Li. "An Acoustic Source Model for Applications in Low Mach Number Turbulent Flows, Such as a Large-Scale Wind Turbine Blade." Energies 12, no. 23 (2019): 4596. http://dx.doi.org/10.3390/en12234596.

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Aerodynamic noise from wind turbine blades is one of the major hindrances for the widespread use of large-scale wind turbines generating green energy. In order to more accurately guide wind turbine blade manufacturers to optimize the blade geometry for aerodynamic noise reduction, an acoustic model that not only understands the relation between the behavior of the sound source and the sound generation, but also accounts for the compressibility effect, was derived by rearranging the continuity and Navier–Stokes equations as a wave equation with a lump of source terms, including the material der

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Ku, Garam, Songjune Lee, Cheolung Cheong, Woong Kang, and Kuksu Kim. "Development of High-Fidelity Numerical Methodology Based on Wavenumber-Frequency Transform for Quantifying Internal Aerodynamic Noise in Critical Nozzle." Applied Sciences 9, no. 14 (2019): 2885. http://dx.doi.org/10.3390/app9142885.

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In industrial fields dealing with high-temperature and high-pressure gas such as chemical, petrochemical, and offshore oil production plants, piping systems with valves are frequently used to protect the relevant system and equipment from being damaged by such gases. However, excessive noise is sometimes generated by the valve flow in the piping system, causing so-called acoustic induced vibration in the pipe wall. Therefore, it is of great importance to design the related system to avoid this phenomenon. In this study, a high-fidelity numerical procedure is proposed to assess the acoustic pow

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Yang, Dang Guo, Yong Hang Wu, Jin Min Liang, and Jun Liu. "An Investigation on Numerical Simulation Method for Aero-Acoustics Based on Acoustics Analogy." Applied Mechanics and Materials 444-445 (October 2013): 462–67. http://dx.doi.org/10.4028/www.scientific.net/amm.444-445.462.

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A numerical simulation method on noise prediction, which incorporates aerodynamics and sound wave equations based on acoustic analogy, is presented in the paper. Near-field unsteady aerodynamic characteristic can be obtain by large eddy simulation (LES), and far-field propagation of sound waves and spatial sound-field can be obtain by solving the time-domain integral equations of Ffowcs Williams and Hawings (FW-H). Based on the method, a numerical simulation was done on a two-dimension cylinder and a three-dimension flat plate with blunt leading edge. The agreement of numerical results with ex

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Tao, Jun, Gang Sun, Ying Hu, and Miao Zhang. "Noise Prediction for Multi-Element Airfoil Based on FW-H Equation." Applied Mechanics and Materials 52-54 (March 2011): 1388–93. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.1388.

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In this article, four observation points are selected in the flow field when predicting aerodynamic noise of a multi-element airfoil for both a coarser grid and a finer grid. Numerical simulation of N-S equations is employed to obtain near-field acoustic information, then far-field acoustic information is obtained through acoustic analogy theory combined with FW-H equation. Computation indicates: the codes calculate the flow field in good agreement with the experimental data; The finer the grid is, the more stable the calculated sound pressure level (SPL) is and the more regularly d(SPL)/d(St)

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Stathopoulos, Elaine T., and Christine M. Sapienza. "Developmental Changes in Laryngeal and Respiratory Function With Variations in Sound Pressure Level." Journal of Speech, Language, and Hearing Research 40, no. 3 (1997): 595–614. http://dx.doi.org/10.1044/jslhr.4003.595.

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The development of the speech production system was investigated using a crosssectional design that included children aged 4–14 years and adults. Given that the size and internal structure of the laryngeal and respiratory systems differ between children and adults, it was predicted that children would show functional distinctions from adults during speech. Aerodynamic, acoustic, and respiratory kinematic techniques were used to assess laryngeal and respiratory function while participants varied their sound pressure level. In general, the aerodynamic and acoustic results show that men and 14-ye

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Krasheninnikov, Sergey Ju, Alexey K. Mironov, Evgeny V. Pavlyukov, Andrey V. Shenkin, and Vladimir K. Zhitenev. "Mixer-Ejector Nozzles: Acoustic and Thrust Characteristics." International Journal of Aeroacoustics 4, no. 3 (2005): 267–88. http://dx.doi.org/10.1260/1475472054771448.

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The paper presents the review of the CIAM/TsAGI investigations of mixer-ejector models, which could be considered to be prototypes of real variable area nozzles for future supersonic aircraft. Acoustic and aerodynamic characteristics of both 2-D and axisymmetrical models were obtained. The influence of nozzle geometry (number of lobes, lobe shape, ejector length, auxiliary inlets in the ejector walls) on its noise and thrust performances is discussed. The experimental data show that the best mixer-ejector configuration tested provides a noise reduction efficiency of about 3 ∼ 3.5 PNdB per 1% t

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Demolin, Didier, Hubert Ngonga-Ke-Mbembe, and Alain Soquet. "Phonetic characteristics of an unexploded palatal implosive in Hendo." Journal of the International Phonetic Association 32, no. 1 (2002): 1–15. http://dx.doi.org/10.1017/s0025100302000117.

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This paper describes the phonetic characteristics of an unexploded palatal implosive in Hendo, a Bantu language spoken in the Democratic Republic of Congo. This sound is an allophone of a palatal affricate implosive. Consideration of acoustic, aerodynamic and articulatory data obtained from various methods give a precise description of this sound.

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Stoakes, Hywel M., Janet M. Fletcher, and Andrew R. Butcher. "Nasal coarticulation in Bininj Kunwok: An aerodynamic analysis." Journal of the International Phonetic Association 50, no. 3 (2019): 305–32. http://dx.doi.org/10.1017/s0025100318000282.

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Bininj Kunwok (BKw), a language spoken in Northern Australia, restricts the degree of anticipatory nasalization, as suggested by previous aerodynamic and acoustic analyses (Butcher 1999). The current study uses aerodynamic measurements of speech to investigate patterns of nasalization and nasal articulation in Bininj Kunwok to compare with Australian languages more generally. The role of nasal coarticulation in ensuring language compre-hensibility a key question in phonetics research today is explored. Nasal aerodynamics is measured in intervocalic, word-medial nasals in the speech of five fem

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Nusser, Katrin, and Stefan Becker. "Numerical investigation of the fluid structure acoustics interaction on a simplified car model." Acta Acustica 5 (2021): 22. http://dx.doi.org/10.1051/aacus/2021014.

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Part of vehicle interior noise is caused by the complex turbulent flow field behind the a-pillar and side mirror. It excites the structure of the side window, which radiates noise into the interior. Both aerodynamic pressure excitation and acoustic sound sources in the flow play an important role. In this work, the influence of both excitation mechanisms is investigated numerically in a hybrid simulation on a simplified car geometry. The generic model allows for an exact definition of boundary conditions and good reproducibility of simulation results. An incompressible Large-Eddy-Simulation (L

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Brind, James, and Graham Pullan. "Modelling Turbine Acoustic Impedance." International Journal of Turbomachinery, Propulsion and Power 6, no. 2 (2021): 18. http://dx.doi.org/10.3390/ijtpp6020018.

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We quantify the sensitivity of turbine acoustic impedance to aerodynamic design parameters. Impedance boundary conditions are an influential yet uncertain parameter in predicting the thermoacoustic stability of gas turbine combustors. We extend the semi-actuator disk model to cambered blades, using non-linear time-domain computations of turbine vane and stage cascades with acoustic forcing for validation data. Discretising cambered aerofoils into multiple disks improves reflection coefficient predictions, reducing error by up to an order of magnitude compared to a flat plate assumption. A para

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Gourdain, Nicolas, Thierry Jardin, Ronan Serre, Sébastien Prothin, and Jean-Marc Moschetta. "Application of a lattice Boltzmann method to some challenges related to micro-air vehicles." International Journal of Micro Air Vehicles 10, no. 3 (2018): 285–99. http://dx.doi.org/10.1177/1756829318794174.

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The demand for micro-air vehicles is increasing as well as their potential missions. Whether for discretion in military operations or noise pollution in civilian use, the improvement of aerodynamic and acoustic performance of micro-air vehicles propeller is a goal to achieve. Micro- and nano-air vehicles operate at Reynolds numbers ranging from 103 to 105. In these conditions, the aerodynamic performance of conventional fixed and rotary wings concepts drastically decreases due to the increased importance of flow viscous forces that tend to increase drag and promote flow separation, which leads

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Geng, Biao, Xudong Zheng, Qian Xue, Geng Liu, and Haibo Dong. "A Numerical Study of the Sound and Force Production of Flexible Insect Wings." Fluids 3, no. 4 (2018): 87. http://dx.doi.org/10.3390/fluids3040087.

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We numerically solved the acoustic and flow field around cicada wing models with parametrically varied flexibility using the hydrodynamic/acoustic splitting method. We observed a gradual change of sound directivity with flexibility. We found that flexible wings generally produce lower sound due to reduced aerodynamic forces, which were further found to scale with the dynamic pressure force defined as the integration of dynamic pressure over the wing area. Unlike conventional scaling where the incoming flow velocity is used as the reference to calculate the force coefficients, here only the nor

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Zajac, David J. "Maximizing Clinical Acquisition and Interpretation of Aerodynamic and Acoustic Speech Data in Children With Velopharyngeal Dysfunction." Perspectives on Speech Science and Orofacial Disorders 15, no. 2 (2005): 11–14. http://dx.doi.org/10.1044/ssod15.2.11.

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Mickiewicz, Witold. "Particle Image Velocimetry and Proper Orthogonal Decomposition Applied to Aerodynamic Sound Source Region Visualization in Organ Flue Pipe." Archives of Acoustics 40, no. 4 (2015): 475–84. http://dx.doi.org/10.1515/aoa-2015-0047.

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AbstractThe paper presents experimental results of the visualization of the nonlinear aeroacoustic sound generation phenomena occurring in organ flue pipe. The phase-locked particle image velocimetry technique is applied to visualize the mixed velocity field in the transparent organ flue pipe model made from Plexiglas. Presented measurements were done using synchronization to the tone generated by the pipe itself sup- plied by controlled air flow with seeding particles. The time series of raw velocity field distribution images show nonlinear sound generation mechanisms: the large amplitude of

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Holmberg, Eva B., Robert E. Hillman, Joseph S. Perkell, Peter C. Guiod, and Susan L. Goldman. "Comparisons Among Aerodynamic, Electroglottographic, and Acoustic Spectral Measures of Female Voice." Journal of Speech, Language, and Hearing Research 38, no. 6 (1995): 1212–23. http://dx.doi.org/10.1044/jshr.3806.1212.

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This study examines measures of the glottal airflow waveform, the electroglottographic signal (EGG), amplitude differences between peaks in the acoustic spectrum, and observations of the spectral energy content of the third formant (F3), in terms of how they relate to one another. Twenty females with normal voices served as subjects. Both group and individual data were studied. Measurements were made for the vowel in two speech tasks: strings of the syllable /pæ/ and sustained phonation of /æ/, which were produced at two levels of vocal effort: comfortable and loud voice. The main results were

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Wright, T., and W. E. Simmons. "Blade Sweep for Low-Speed Axial Fans." Journal of Turbomachinery 112, no. 1 (1990): 151–58. http://dx.doi.org/10.1115/1.2927413.

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The available literature on aerodynamic and acoustic properties of axial fans with swept blades is presented and discussed with particular emphasis on noise mechanisms and the influence of high-intensity inlet turbulence on “excess” noise. The acoustic theory of Kerschen and Envia for swept cascades is applied to the problem of axial fan design. These results are compared to available data and a provisional model for specifying sweep angles is presented. The aerodynamic performance theory for swept-bladed rotors of Smith and Yeh is adapted for use in designing low-speed axial fans. Three proto

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Taratorin, Andrey, and Vladimir Tupov. "PETAL-SHAPED SILENCERS USAGE FOR NOISE REDUCTION IN CYLINDRICAL CHANNELS." VOLUME 39, VOLUME 39 (2021): 99. http://dx.doi.org/10.36336/akustika20213999.

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The article presents data on the results of petal-shaped silencer mathematical modeling. Dissipative silencers of complex shapes are the most promising technology. This design allows for achieving the required noise reduction. At the same time, geometric shape optimization allows reducing the aerodynamic drag to the smallest values. The article compares the variants of the silencer with the rotation angles of the plates 45 and 70 degrees. The use of such plates allows you to increase the acoustic efficiency of the silencer by eliminating the radiation effect. In the article, there are the resu

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Liu, Xiaomin, and Xiang Liu. "A Numerical Study of Aerodynamic Performance and Noise of a Bionic Airfoil Based on Owl Wing." Advances in Mechanical Engineering 6 (January 1, 2014): 859308. http://dx.doi.org/10.1155/2014/859308.

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Noise reduction and efficiency enhancement are the two important directions in the development of the multiblade centrifugal fan. In this study, we attempt to develop a bionic airfoil based on the owl wing and investigate its aerodynamic performance and noise-reduction mechanism at the relatively low Reynolds number. Firstly, according to the geometric characteristics of the owl wing, a bionic airfoil is constructed as the object of study at Reynolds number of 12,300. Secondly, the large eddy simulation (LES) with the Smagorinsky model is adopted to numerically simulate the unsteady flow field

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Grillo, Elizabeth U. "A phrase captures aerodynamic and acoustic data in healthy voice users and in patients with voice disorders." Logopedics Phoniatrics Vocology 45, no. 1 (2018): 24–29. http://dx.doi.org/10.1080/14015439.2018.1545866.

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Kwon, Tack-Kyun, Woo-Jin Jeong, Myung-Whun Sung, and Kwang Hyun Kim. "Development of Endoscopic Arytenoid Adduction Using Cricoid Implant." Annals of Otology, Rhinology & Laryngology 116, no. 10 (2007): 770–78. http://dx.doi.org/10.1177/000348940711601009.

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Objectives: We sought to develop a less-invasive alternative to conventional arytenoid adduction using a cricoid implant. Methods: We performed a preliminary study with excised human and canine larynges. A nail-shaped stainless steel rod and an insertion device were designed for an in vivo animal trial. After unilateral recurrent laryngeal denervation surgery in 5 adult mongrel dogs, the implants were inserted endoscopically through a small mucosal incision over the cricoarytenoid joint. Acoustic and aerodynamic data were obtained from each animal before serial euthanasia followed by examinati

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Zhang, Yong Ou, Tao Zhang, and Tian Yun Li. "Flow-Induced Noise Simulation Based on LES/Lighthill Hybrid Method." Applied Mechanics and Materials 614 (September 2014): 428–31. http://dx.doi.org/10.4028/www.scientific.net/amm.614.428.

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A hybrid numerical method of combining Large Eddy Simulation (LES) and Lighthill’s acoustic analogy theory is utilized to simulate the flow-induced noise at low Mach numbers. The aerodynamic noise generated by flow through a cavity, which is similar to a valve, is simulated and the results are validated by comparing with the open literature. In the simulation, the turbulent flow is computed with LES. After this, the flow field simulation results are used to compute the flow-induced noise with Lighthill’s acoustic analogy theory based on the commercial software ACTRAN. Finally, the simulation r

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Cho, Yong, and Young J. Moon. "Discrete Noise Prediction of Variable Pitch Cross-Flow Fans by Unsteady Navier-Stokes Computations." Journal of Fluids Engineering 125, no. 3 (2003): 543–50. http://dx.doi.org/10.1115/1.1568356.

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The unsteady viscous flow fields of a cross-flow fan are computed by time-accurately solving the two-dimensional incompressible Navier-Stokes equations with the unstructured triangular mesh solver algorithms. Based on pressure fluctuation data acquired at the surfaces of 35 rotating blades and stabilizer, acoustic pressures are predicted by the Ffowcs Williams-Hawkings equation. The aerodynamic noise sources of the cross-flow fan are also identified by correlating the acoustic pressure fluctuations with the unsteady flow characteristics during one revolution of the impeller. The present method

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Battista, Gianmarco, Paolo Chiariotti, Milena Martarelli, Paolo Castellini, Claudio Colangeli, and Karl Janssens. "3D Acoustic Mapping in Automotive Wind Tunnel: Algorithm and Problem Analysis on Simulated Data." Applied Sciences 11, no. 7 (2021): 3241. http://dx.doi.org/10.3390/app11073241.

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Localization and quantification of noise sources are important to fulfill customer and regulation requirements in a such competitive sector like automotive manufacturing. Wind tunnel testing and acoustic mapping techniques based on microphone arrays can provide accurate information on these aspects. However, it is not straightforward to get source positions and strengths in these testing conditions. In fact, the car is a 3D object that radiates noise from different parts simultaneously, involving different noise generation mechanisms such as tire noise and aerodynamic noise. Commonly, acoustic

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Bernardini, Giovanni, Francesco Centracchio, Massimo Gennaretti, et al. "Numerical Characterisation of the Aeroacoustic Signature of Propeller Arrays for Distributed Electric Propulsion." Applied Sciences 10, no. 8 (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 fur

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Perkell, Joseph S., Eva B. Holmberg, and Robert E. Hillman. "A system for signal processing and data extraction from aerodynamic, acoustic, and electroglottographic signals in the study of voice production." Journal of the Acoustical Society of America 89, no. 4 (1991): 1777–81. http://dx.doi.org/10.1121/1.401011.

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Haufe, Daniel, Johannes Gürtler, Anita Schulz, Friedrich Bake, Lars Enghardt, and Jürgen Czarske. "Aeroacoustic analysis using natural Helmholtz–Hodge decomposition." Journal of Sensors and Sensor Systems 7, no. 1 (2018): 113–22. http://dx.doi.org/10.5194/jsss-7-113-2018.

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Abstract. The analysis of aeroacoustic phenomena is crucial for a deeper understanding of the damping mechanisms of a sound-absorbing bias flow liner (BFL). For this purpose, simultaneous measurements of the sound field and the flow field in a BFL are required. The fluid velocity can serve as the measurand, where both the acoustic particle velocity and the aerodynamic flow velocity contribute and, thus, can be acquired simultaneously. However, there is a need to separate these two quantities to distinguish between them. This is challenging because they generally coincide with each other in the

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Van Zante, D. E., F. Collier, A. Orton, S. Arif Khalid, J. P. Wojno, and T. H. Wood. "Progress in open rotor propulsors: The FAA/GE/NASA open rotor test campaign." Aeronautical Journal 118, no. 1208 (2014): 1181–213. http://dx.doi.org/10.1017/s0001924000009842.

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Abstract Model scale tests of modern ‘open rotor’ propulsor concepts that have potential for significant fuel burn reduction for aircraft applications were completed at NASA Glenn Research Center. The recent test campaign was a collaboration between NASA, FAA, and General Electric (GE). GE was the primary industrial partner, but other organisations were involved such as Boeing and Airbus who provided additional hardware for fuselage simulations. The open rotor is a modern version of the UnDucted Fan (UDF®) that was flight tested in the late 1980s through a partnership between NASA and GE. The

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Kholodov, Pavel, and Stéphane Moreau. "Identification of Noise Sources in a Realistic Turbofan Rotor Using Large Eddy Simulation." Acoustics 2, no. 3 (2020): 691–706. http://dx.doi.org/10.3390/acoustics2030037.

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Large Eddy Simulation is performed using the NASA Source Diagnostic Test turbofan at approach conditions (62% of the design speed). The simulation is performed in a periodic domain containing one fan blade (rotor-alone configuration). The aerodynamic and acoustic results are compared with experimental data. The dilatation field and the dynamic mode decomposition (DMD) are employed to reveal the noise sources around the rotor. The trailing-edge radiation is effective starting from 50% of span. The strongest DMD modes come from the tip region. Two major noise contributors are shown, the first be

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