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会议信息

会议名称:

AIAA/CEAS aeroacoustics conference

召开年:

2017

召开地:

Denver

会议文集:

23rd AIAA/CEAS aeroacoustics conference 2017: 23rd AIAA/CEAS aeroacoustics conference 2017, 5-9 June 2017, Denver, Colorado, USA

主办单位:

American Institute of Aeronautics and Astronautics

出版时间:

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  • 题名 作者 来源 发表时间 操作
  • Turbulent Flow Interaction with Porous Surfaces

    作者:Syamir Alihan Showkat Ali;Mate Szoke;Mahdi Azarpeyvand;Carlos R. Ilario da Silva; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    The interaction of a standard boundary layer with a rough porous surface has been investigated experimentally. Comprehensive boundary layer and surface pressure measurements have been carried out using a long flat plate equipped with several streamwise and span-wise surface pressure transducers. To reveal the effects of the interaction of a boundary layer with a porous surface, three types of porous materials with different porosity and permeability constants are examined. Results have shown that porous surface treatments can significantly alter the boundary layer flow properties and cause significant changes to the energy cascade of the velocity fluctuations within the boundary layer. It has also been shown that porous surfaces cause a reduction in the high-frequency energy content of the surface pressure fluctuations. Moreover, it has been found that the use of a porous surface can lead to a significant reduction in the spanwise coherence and the length-scales of the boundary layer flow structures. The emergence of a strong hydrodynamic field inside the highly permeable surfaces has also been explored. The results presented in this paper are of great importance for the better understanding of the flow-porous interaction mechanisms and have demonstrated that our understanding of the problem is limited and more high-quality experiments are required for the development of bespoke passive porous-based flow and noise control techniques.

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  • Turbulent Flow Interaction with Porous Surfaces

    Syamir Alihan Showkat Ali;Mate Szoke;Mahdi Azarpeyvand;Carlos R. Ilario da Silva;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • On the spatial-temporal development of turbulent spots on a serrated trailing edge

    作者:A. Juknevicius;T. P. Chong; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Aim of the paper is to investigate the flow in the close vicinity of flat-plate insert-type trailing edge serrations. It is now firmly established that aerofoil subjected to a serrated trailing edge is quiet. Recent advances in the analytical and numerical solutions have established several mechanisms that can help to explain the causes of the lower level of self-noise radiation by a serrated aerofoil. Some high fidelity experimental works, such as the time-resolved Particle Image Velocimetry (PIV), have been used recently to track the evolution of a fully-developed turbulent boundary layer flow structures over a serrated trailing edge. However, due to the high cost and technical challenging, the time-resolved PIV measurements still have some limitations in the construction of a complete spatial and temporal evolution of these small-scale turbulent structures. The current work seeks to develop a simple technique by artificially generating the turbulent spots - the so called "building block" of the turbulent boundary layer, and to track in the space and time domains a complete evolution of these spots over the serrated trailing edge of an aerofoil using the ensemble-averaging analysis method for the hot-wire data. The test was conducted on a symmetrical NACA0008 aerofoil under zero-lift conditions and at a Reynolds number 1.12 × 10~5. Aero-acoustic measurements at these conditions confirm that significant broadband self-noise reduction can be achieved by a serrated trailing edge. After gathering the relevant boundary layer data, a preliminary examination of the velocity perturbation and turbulence intensity distributions near the straight trailing edge would confirm the classical turbulent spot structure that can typically be found in the literature. However, in the case of a serrated trailing edge, it is observed that each passage of a turbulent spot, especially at its so called 'calm region', would draw high momentum flow (i.e. positive velocity perturbation) periodically from the sawtooth gap towards the sawtooth surface. It is believed that this periodic calming and stabilization effect of the boundary layer might represent the general mechanism for the reduction of the self-noise generated at the trailing edge, although currently more data analysis is still underway to dissect the internal flow details of the turbulent spot at the serrated trailing edge.

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  • On the spatial-temporal development of turbulent spots on a serrated trailing edge

    A. Juknevicius;T. P. Chong;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Two-dimensional Modal Beamforming in Wavenumber Space for Duct Acoustics

    作者:Robert P. Dougherty;Richard F. Bozak; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    As turbofan bypass ratio continues to increase, civilian aircraft noise is increasingly dominated by fan noise. Fan noise propagating from its rotor and stator origins to the community passes through the inlet or aft flow duct, where its confined situation makes it susceptible to characterization by wall-mounted microphone arrays. Recently, the NASA-Glenn Research Center adapted its W-8 Single Stage Axial Compressor Facility to this type of measurement. OptiNav, Inc. took the opportunity to improve and simplify the duct mode processing in its Beamform Interactive computer program. A new approach to in-duct beamforming with a 2D wall-mounted array of microphones was developed. The purpose of this paper is to document the beamforming approach and provide some sample results from the W-8 facility.

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  • Two-dimensional Modal Beamforming in Wavenumber Space for Duct Acoustics

    Robert P. Dougherty;Richard F. Bozak;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • A Tomographic Directivity Approach to Frequency Domain Beamforming

    作者:Thomas Ahlefeldt;Carsten Spehr;Tobias Berkefeld;Alessandro Di Marco;Lorenzo Burghignoli; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Aeroacoustic measurements in wind tunnels are a common tool in the determination of sound sources on scaled models. Most of the algorithms used are based on the assumption that the unknown aeroacoustic sources radiate sound waves omnidirectionally, thus monopole sources are utilized. For the prediction of the noise footprint of aircrafts however, it is essential to have information on the directivity of the airframe sources. An approach to estimating this directivity is to use different array positions for measurement relative to the model which leads to different observation angles. The evaluation of measurements at several observation angles holds several issues, for example the difficult source localization due to the three-dimensionality of the point spread function and partial shadowing of sources at large observation angles. This paper therefore presents an approach to estimate the source positions taking into account information from all four observation angles at once. The positions estimated in this fashion are subsequently used for an improved prediction of source power and eventually lead to an estimation of directivity of the observed aeroacoustic sources.

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  • A Tomographic Directivity Approach to Frequency Domain Beamforming

    Thomas Ahlefeldt;Carsten Spehr;Tobias Berkefeld;Alessandro Di Marco;Lorenzo Burghignoli;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Trailing-edge noise in slowly varying, sheared flow

    作者:David I. Baker;Nigel Peake; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Under a transformation to streamline coordinates, it is possible to generalise Rapid Distortion Theory results, applied to sheared flow, to include a developing flow. This allows inclusion of large geometrical effects, for example a thick aerofoil, to high-frequency acoustic disturbances. These ideas are developed by considering a shear flow passing over a protrusion from a wall, and extended to include the effect of a trailing-edge.

    关键字:

  • Trailing-edge noise in slowly varying, sheared flow

    David I. Baker;Nigel Peake;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Numerical Study of 2-D Finlets Using RANS CFD for Trailing Edge Noise Reduction

    作者:Yuejun Shi;Seongkyu Lee; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    This paper presents a numerical study of 2-D finlets using RANS CFD to investigate their physical mechanism of trailing edge noise reduction. An empirical wall pressure spectrum model and Howe's diffraction model are used to predict trailing edge noise based on boundary layer parameters provided by RANS CFD. This numerical approach enables fast and accurate predictions of trailing edge noise, which is used to study the noise reduction with finlets for various airfoil geometries and flow conditions at high Reynolds number. Two types of finlets, the suction-side (inlet and the pressure-side finlet, are studied. The results show that both types of finelts are able to reduce far-field noise up to 10 dB compared to clean airfoils. It is found that the suction-side finlet reduces noise at low and middle frequencies while the pressure-side finlet reduces noise at high frequencies. Sensitivity study is conducted to show the independence of the predictions on the wall pressure spectrum measuring point. Also, finlets with four different heights are compared with each other to investigate the effect of the height of finlets on noise reduction. In order to understand the physical mechanism of noise reduction with a finlet, flow variables such as turbulence kinetic energy and streamwise velocity near the trailing edge are investigated for airfoils with and without a finlet. It is demonstrated that a finlet reduces turbulence kinetic energy near the wall, which is further supported by velocity deficits in that region. A possible physical mechanism is proposed through synthesizing obtained results. Overall, this paper demonstrates potential of finlets in trailing edge noise reduction and sheds light on the physics of observed phenomena.

    关键字:

  • Numerical Study of 2-D Finlets Using RANS CFD for Trailing Edge Noise Reduction

    Yuejun Shi;Seongkyu Lee;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Airfoil Trailing-edge Noise Reduction using Flow Suction

    作者:Luana Maciel Cesar;Hasan Kamliya Jawahar;Mahdi Azarpeyvand; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Large eddy simulations were carried out for a NACA-0012 airfoil with trailing edge flow suction at the angle of attack a = 0° for a chord-based Reynolds number of Re, = 4x 10~5. Simulations were performed with different flow suction rates to demonstrate the viability of the technique. The baseline case was thoroughly validated with experimental data. The aerodynamic and aeroacoustic characteristics of the boundary layer and wake were studied in detail for different flow suction rates. The mean velocity results showed reduced wake velocity deficit. Results have also shown that the suction of the boundary flow upstream of the trailing edge can reduce the boundary layer and wake turbulent kinetic energy and significant reduction of the wall pressure spectra near the trailing edge. The effect of flow suction on the spanwise correlation length has also been studied. The results have shown that a moderate flow suction rate can result in partial flow laminarization, broadband reduction of the surface pressure spectra and the radiated noise from the trailing edge.

    关键字:

  • Airfoil Trailing-edge Noise Reduction using Flow Suction

    Luana Maciel Cesar;Hasan Kamliya Jawahar;Mahdi Azarpeyvand;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Noise and Sonic Boom Analysis from Rocket Launches

    作者:Kevyn Tran;Dongwook Lim;Sanggyu Min;Kihoon Oh;Dimitri Mavris; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Despite the increase of rocket launches in the past years and the commercialization of their operations, little work has been published assessing the community noise impacts from rocket operations. Thus, noise modeling studies can help better understand potential noise exposures to the surrounding communities from rocket launches at spaceports. The introduction of two tools, RUMBLE and PCBoom, allow further research to be completed than previously because of their abilities to model rocket noise and sonic booms to allow predictions of how future launch operations will affect surrounding communities. The added benefit of using these two programs is the ability to integrate their results into the FAA's Aviation Environmental Design Tool (AEDT) in order to combine rocket noise with aircraft noise. This is particularly important because many spaceports currently serve as airports and will continue to be airports servicing both aircraft and spacecraft. This study will run various future launch scenarios in order to determine the effects of noise associated to rocket launches on the surrounding community.

    关键字:

  • Noise and Sonic Boom Analysis from Rocket Launches

    Kevyn Tran;Dongwook Lim;Sanggyu Min;Kihoon Oh;Dimitri Mavris;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Preliminary noise assessment of aircraft with distributed electric propulsion

    作者:Athanasios P. Synodinos;Rod H. Self;Antonio J. Torija; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Electric and hybrid-electric propulsion technologies are an increasingly attractive option for aviation stakeholders, providing more reliable and efficient power plants than traditional internal combustion engines, while reducing the dependency on fossil fuels, such as oil, whose value is volatile and availability uncertain. Combined with distributed electric propulsion (DEP), these propulsion technologies have shown significant potential in reducing civil aircraft noise emissions and are therefore viable candidates for delivering the strict mid-to-longterm environmental goals set by aviation organisations worldwide, such as ACARE and NASA. This paper examines the noise emission of a concept tube and wing aircraft that falls in the A320 category and features DEP systems using two different power supply units (turboshaft engines or batteries) and a varying number of propulsors. The transition of conventional propulsory systems to electric and hybrid systems is discussed, with Noise-Power-Distance (NPD) curves and noise exposure contour maps computed for several DEP systems and propulsor number configurations. Noise benefits of DEP especially at takeoff are demonstrated, whereas it is shown that based on predicted year 2035 entry into service technology, All Electric aircraft exhibit a larger noise footprint than aircraft using hybrid electric propulsion systems. Finally, our analysis indicates that the number of propulsors is a key parameter that may be used to optimise the environmental performance and noise benefits of DEP aircraft.

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  • Preliminary noise assessment of aircraft with distributed electric propulsion

    Athanasios P. Synodinos;Rod H. Self;Antonio J. Torija;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Community noise assessment for aircrafts with contra- rotating open rotor power plants

    作者:L. Sanders; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    This paper addresses the assessment of the community noise predictions for aircrafts equipped with an innovative propulsion, namely the contra-rotating open rotor (CROR). The paper proposes a CROR noise prediction model based on both empirical observation and theoretical considerations. For the tonal noise, it is based on the propeller noise theory and load modelling from flow simulation results. It requires global characteritics of the propellers such as thrust, blades number and propellers diameters so it can be included in an aircraft design tool in order to provide a quick noise evaluation. This CROR tonal noise prediction model is compared against Computational Fluid Dynamics (CFD) and acoustic analogy. Despite of several discrepancies on specific tones, it offers a global agreement. Besides, a basic broadband noise model for CROR is included. It is based on results produced by semi-analytical models from the literature. In that manner, ground noise levels are computed for an aircraft flyover. The accuracy of the ground noise prediction are assessed by a convergence study. Finally, the simulation based on the prediction model for the tonal noise shows discrepancies with the simulation based on high fidelity simulation in the order of 0.5 to 1.5 EPNdB.

    关键字:

  • Community noise assessment for aircrafts with contra- rotating open rotor power plants

    L. Sanders;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Experimental Study of Noise Shielding by a NACA 0012 Airfoil

    作者:Florence V. Hutcheson;Christopher J. Bahr;Russell H. Thomas;Daniel J. Stead; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    The effects of sound source location, Mach number and angle of attack on the shielding of a laser-induced sound source by a NACA 0012 airfoil are examined. The sound source is a small plasma generated by a high energy, laser beam focused to a point. In-flow microphone measurements are acquired in the midspan plane of the airfoil over a broad range of streamwise stations, and shielding levels are calculated over different frequency ranges from the measurements acquired with and without the airfoil installed. Shielding levels are shown to increase as the source is positioned closer to the midchord of the airfoil, and to significantly decrease with increasing flow Mach number, except when the source is positioned near the leading edge of the airfoil. Both with and without flow, changes in angle of attack are associated with a corresponding shift of the shadow region. Finally, the effects of multipath signals, observer distance and signal scatter on the measured shielding levels are discussed.

    关键字:

  • Experimental Study of Noise Shielding by a NACA 0012 Airfoil

    Florence V. Hutcheson;Christopher J. Bahr;Russell H. Thomas;Daniel J. Stead;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Computation and Validiation of Acoustic Shielding at Realistic Aircraft Configurations

    作者:Markus Lummer;Michael Moessner;Jan W. Delfs; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    1Acoustic shielding calculations were performed for a generic test object (NACA 0012) and two realistic aircraft configurations, an Unmanned Aerial Vehicle (UAV) and a Hybrid Wing Body (HVVB), and compared with experimental data, where the monopole sound source was realized using laser pulses. The agreement between calculation and experiment is good. Due to wind tunnel size limits experimental data are often restricted to the acoustic nearfield and its usability for farfield shielding predictions must be assessed numerically. In the present paper, shielding patterns were defined and its evolution with increasing distance from the geometry was studied using a simple shifting and scaling procedure. For higher frequencies, a linear scaling of the patterns with increasing distance could be established.

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  • Computation and Validiation of Acoustic Shielding at Realistic Aircraft Configurations

    Markus Lummer;Michael Moessner;Jan W. Delfs;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Simulations and experiments of dual high-speed impinging jets

    作者:Mary L. Houston;Joseph W. Nichols;Fernando Zigunov;Prabu Sellappan;Farrukh Alvi; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Aeroacoustic characteristics of small diameter high-speed impinging jets are investigated experimentally and numerically. A single round jet perpendicularly striking a flat surface generates loud, tonal noise due to the resonance between instabilities in the jet shear layer and acoustic feedback from the impingement plate. The addition of a second impinging jet placed laterally near to the first disrupts this tone generating mechanism. These phenomena are investigated experimentally using Schlieren imaging and near-field microphone measurements. We also apply high-fidelity Large Eddy Simulation (LES) using unstructured meshes to resolve the entire three dimensional flow field and compare to experimental measurements. We consider under expanded cold jets of design Mach numbers 1 and 1.5 operating in isolation, as well as a flow field where the two jets are laterally placed at 4.5 jet diameters. We investigate the acoustic properties of the simulated flow fields by extracting frequency information from pressure measurements in the shear layer. We identify shear layer features that are most significant in generation of near-field noise.

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  • Simulations and experiments of dual high-speed impinging jets

    Mary L. Houston;Joseph W. Nichols;Fernando Zigunov;Prabu Sellappan;Farrukh Alvi;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Temperature effect on the apparent position of effective noise sources in a hot jet

    作者:V.Gryazev;A.Markesteijn;S.Karabasov; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    Far-field noise radiated by an analytical ring source model is calculated in accordance with the Goldstein generalised acoustic analogy. The source represents the fluctuating Reynolds stress term and its directivity corresponds to the source strength directivity extracted from a Large Eddy Simulation of the static heated subsonic SILOET jet case at temperature ratio 2.5. For far-field sound propagation, a locally parallel flow model is applied with taking into account the sound speed variation across the jet thermal layer, which is implemented and validated in MATLAB. This model is compared with an approximate propagation model that accounts for locally meanflow propagation but ignores the sound speed variation effect. The far-field noise predictions of the two models are compared for a range of the source locations in the shear layer, sound frequencies, and observer angles to answer the question when the omission of variable sound speed in a heated jet can be justified.

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  • Temperature effect on the apparent position of effective noise sources in a hot jet

    V.Gryazev;A.Markesteijn;S.Karabasov;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Feedback Control of Flight Speed to Reduce Unmanned Aerial System Noise

    作者:Matthew B. Galles;Noah H. Schiller;Kasey A. Ackerman;Brett Newman; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    The aim of this initial study was to incorporate an acoustic metric into the flight control system of an unmanned aerial vehicle. This could be used to mitigate the noise impact of unmanned aerial systems operating near residential communities. To incorporate an acoustic metric into a flight control system, two things were required: a source noise model, and an acoustic controller. An acoustic model was developed based on Gutin's work to estimate propeller noise. The flight control system was augmented with a controller to reduce propeller noise using feedback control of the commanded flight speed until an acoustic target was met. This control approach focused on modifying flight speed only, with no perturbation to the trajectory. Multiple flight simulations were performed and the results show that integrating an acoustic metric into the flight control system of an unmanned aerial system is possible.

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  • Feedback Control of Flight Speed to Reduce Unmanned Aerial System Noise

    Matthew B. Galles;Noah H. Schiller;Kasey A. Ackerman;Brett Newman;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Electric Motor Noise from Small Quadcopters: Part Ⅰ - Acoustic Measurements

    作者:Dennis L. Huff;Brenda S. Henderson; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    There is increased interest in using electric motors to drive propulsors across a range of small air vehicle classes. Applications include both vertical lift and conventional takeoff and landing systems for Small Unmanned Aircraft Systems. Mission profiles call for integrating these systems into urban airspaces exposing populated areas to new noise sources. In addition to the propulsor noise from rotors and propellers, electric motors are expected to contribute to the overall sound levels and possibly human annoyance. This work presents acoustic measurements of electric motors used for small quadcopters to characterize the sound and identify sources with and without a propeller. Free field microphone measurements were used to determine directivity and a phased microphone array was used to identify sound sources. A companion paper (Part Ⅱ - Source Characteristics and Prediction) compares the far field results with current probe measurements of the signal driving the motor, the structural response of the motor case, and describes prediction methods of electric motor noise.

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  • Electric Motor Noise from Small Quadcopters: Part Ⅰ - Acoustic Measurements

    Dennis L. Huff;Brenda S. Henderson;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Assessing noise effects of the urban air transportation system

    作者:Ivan Terekhov;Malte Niklass;Niclas Dzikus;Volker Gollnick; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    The paper studies air vehicle port spatial distributions within an urban area and their noise impact on population. The aim of the paper is to provide a vision of the tradeoff between the infrastructure size of the urban air transportation system (including potential revenues) and the number of negatively affected by noise produced by the system. It was conducted by modeling a number of air vehicle port distributions for various scenarios for a simulated virtual urban area. The scenarios were assessed by different metrics and the optimal solutions were determined.

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  • Assessing noise effects of the urban air transportation system

    Ivan Terekhov;Malte Niklass;Niclas Dzikus;Volker Gollnick;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • On the Transfer of Leading Edge Serrations from Isolated Aerofoil to Ducted Low-Pressure Fan Application

    作者:Till M. Biedermann;Nils Hintzen;Frank Kameier;T.P. Chong;C. O. Paschereit; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    At high-turbulent inflow conditions, the blades of axial fans are known to emit a significantly increased amount of leading edge broadband noise. Recent research has firmly confirmed leading edge serrations to be an effective passive treatment in noise reduction. Up to now, leading edge serrations are mainly analysed in rigid test settings. With the aim of transferring leading edge serrations from the single aerofoil approach to the full rotor, an experimental rig was developed where a ducted low-pressure fan is installed. The fan blades are designed according to NACA65(12)-10 profiles, which were already analysed extensively in previous experimental and numerical studies. The rig allows to gather the aerodynamic and aeroacoustic data. Altogether, five different parameters can be analysed, namely the serration amplitude and wavelength, the stagger angle, the inflow turbulence and the rotational speed. The presented work focuses on a quantitative aerodynamic and aeroacoustic analysis of the designed rotor, where straight leading edges are compared to five sets of serrated blades, covering the full fan performance characteristics. A clear aeroacoustic sensitivity towards different incoming turbulence intensities was detected where a noise reduction can be observed especially for high serration amplitudes and large wavelengths. The aerodynamic performance primary scales with the ratio of serration wavelength and amplitude.

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  • On the Transfer of Leading Edge Serrations from Isolated Aerofoil to Ducted Low-Pressure Fan Application

    Till M. Biedermann;Nils Hintzen;Frank Kameier;T.P. Chong;C. O. Paschereit;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Investigations on Analytic Models of Broadband Wake-Blade Interaction Noise

    作者:Gabriele Grasso;Stephane Moreau;Julien Christophe;Christophe Schram; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    This work presents an analytic model of fan wake-interaction broadband leading-edge noise based on Amiet's model for the noise emitted by an airfoil in a stream of homogeneous turbulence. In particular, two aspects which have been recently taken into account in the investigation of broadband wake-airfoil interaction noise based on Amiet's theory are here explored. The first is the effect of the inclination of the wavefront of the wake mean-velocity variation with respect to the leading edge of the blade, as opposed to the case where the wake is parallel to the leading edge. The second aspect is the influence of the model adopted to represent the spectrum of turbulent velocity fluctuations on the predicted wake-interaction sound spectra. These issues are investigated by performing a series of parametric studies with turbulence models found in literature, which are characterized by different distributions of the energy among the aerodynamic wavenumbers. The parameters defining the wake-blade interaction phenomenon that have the most significant influence on the PSD of acoustic pressure are identified. Finally, the model developed in the case of a stationary airfoil is extended to rotating sources by implementing a Doppler factor formulation, obtaining a good agreement with a formulation based on rotating dipole Green's functions.

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  • Investigations on Analytic Models of Broadband Wake-Blade Interaction Noise

    Gabriele Grasso;Stephane Moreau;Julien Christophe;Christophe Schram;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

  • Acoustic scattering by 3D elastic plates of composite materials

    作者:Cristiano Pimenta;William R. Wolf;Andre V. G. Cavalieri; 会议名称:AIAA/CEAS aeroacoustics conference;AIAA aviation forum 2018年

    This work presents a study of acoustic scattering by 3D elastic plates made of composite materials. A fast multipole boundary element method is employed to solve the Helmholtz equation subject to boundary conditions consisting of the vibration of the elastic plate. Such boundary conditions are obtained by the solution of a structural modal basis which satisfies the free vibration problem of plates composed of orthotropic materials. The fluid-structure interaction problem is coupled through the linearized Euler equation. An important difference between the composite and aluminum plates is observed in terms of the specific mass, which impacts the fluid-structure coupling. Results demonstrate that the higher frequency propagation of bending waves along composite plates leads to a further noise reduction when compared to elastic aluminum plates. Solutions obtained by two-dimensional plates are compared to those obtained by fully three-dimensional ones. It is shown that the 2D models of composite plates cannot recover the directional aspects of trailing-edge noise scattering by 3D plates due to the spanwise effects of propagation of bending waves that impact on the acoustic solution.

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  • Acoustic scattering by 3D elastic plates of composite materials

    Cristiano Pimenta;William R. Wolf;Andre V. G. Cavalieri;

    AIAA/CEAS aeroacoustics conference;AIAA aviation forum

    2018年

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根据相关法律规定,本平台及其所提供的外文期刊、外文会议、外文学位论文和外文科技报告文献仅供购买服务的用户(即授权用户)为个人目的或课堂教学目的使用,授权用户可以对本平台的文献进行以下合理使用:

(1)通过安全网络访问服务器对网络数据库进行检索;

(2)以个人研究和学习为目的,在线阅读检索结果;

(3)通过文献传递获取电子文献供授权用户个人研究和学习使用;

(4)非以商业营利为目的承担正常教学任务的授权用户,为教学需要,可少量复制文献供教学人员使用,同时应指明作者姓名和文献名称。例如授权用户可少量复制作为教学参考资料的文献供从事课堂教授的教师使用,可少量文献复制到供本单位教学使用的内部网络中的安全计算机上,供选修特定课程的学生在该课程课堂教学期间和地点通过内部网络进行阅读。

3.侵权行为

除上述合理使用方式外,不得以任何方式对本平台全部或者部分文献进行复制、出版、发行、传播、转让、商业或其他开发,授权用户以下(但不仅限于以下)超出合理使用范围的行为,属侵犯知识产权行为,须严格禁止:

(1)把外文文献以公共方式提供给非授权用户使用;

(2)利用外文文献对非授权用户提供文献服务;

(3)利用外文文献进行商业服务或支持商业服务;

(4)利用外文文献内容汇编生成二次产品,提供公共或商业服务;

(5)将外文文献使用在任何其他网站或计算机联网环境中,包括但不仅限于在国际互联网和万维网站上。

4.侵权责任

授权用户应在法律规定的其超出合理使用范围内使用本平台提供的文献,若因授权用户的侵权使用行为被相关权利人主张权利而产生任何纠纷、仲裁、诉讼,或遭到国家相关部门处理,由授权用户承担全部法律责任并使本平台方免责,授权用户还应赔偿因上述原因给本平台方造成的全部直接和间接损失,包括但不限于律师费用、诉讼及仲裁费用、财务费用及差旅费等。一经发现用户的使用情况超出著作权法规定的合理使用范围,本平台有权立即封禁该用户的服务账户,并有权终止向用户提供本协议约定的服务而无须承担违约责任。

5.免责声明

(1)本平台仅为根据您的搜索指令提供搜索服务、数据链接服务和电子邮件原文传递服务,搜索结果和原文数据均来自第三方网站,六维联合不会对第三方网站内容作任何实质性的编辑、整理、修改;

(2)本平台对服务及服务所涉文献信息不作任何明示或暗示的保证,包括但不限于服务一定会满足用户的使用要求、服务的及时性、持续性、安全性、准确性以及服务所涉及文献的准确性、完整行、可靠性;

(3)本平台不保证所提供的服务和服务所涉文献信息来源客观准确,对于任何因信赖或使用获取的文献信息,而给用户造成任何直接或间接损失,本平台均不承担责任;本平台不因用户与任何第三方产生的争议或诉讼承担任何责任。

(4)用户签署本协议即意味着理解且不要求六维联合在发生不可抗力情况下承担责任。不可抗力是指不能合理控制、不可预见或即使预见亦无法避免的事件,包括但不限于政府行为、地震、台风、洪水、火灾或其它天灾、战争或任何其它类似事件。鉴于互联网之特殊性质,不可抗力还包含非因本平台原因导致本服务无法正常运行、服务中断或延迟的情形,包括黑客攻击,电信部门技术调整导致之重大影响,因政府管制而造成之暂时关闭,病毒侵袭,网站升级、系统停机维护或通讯终端、电信设备出现故障导致无法进行数据传输等。

6.其他规定

(1)本协议内容受中华人民共和国法律的约束。如果本协议中任何规定被裁定为无效或不可强制执行,该项规定应被撤销,而其余规定继续有效。

(2)本协议的最终解释权归六维联合。

(3)本协议条款可由六维联合随时全部或部分转让。未经六维联合事先明确书面同意,用户不得以任何方式转让本协议条款。

注意:六维联合未就您或其他人士的某项违约行为采取行动,并不表明六维联合就任何继后或类似的违约事件放弃采取行动的权利。


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