2018 AIAA/CEAS Aeroacoustics Conference最新文献

{"title":"Experimental Study of Noise Shielding by a NACA 0012 Airfoil","authors":"F. Hutcheson, C. Bahr, Russell H. Thomas, Daniel J. Stead","doi":"10.2514/6.2018-2821","DOIUrl":"https://doi.org/10.2514/6.2018-2821","url":null,"abstract":"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 mid-chord 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.","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"16 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131922866","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Helmholtz Resonator Liner with Flexible Walls","authors":"K. Knobloch, L. Enghardt, F. Bake","doi":"10.2514/6.2018-4102","DOIUrl":"https://doi.org/10.2514/6.2018-4102","url":null,"abstract":"Liners are part of every modern commercial aero-engine. Usually, they are installed in the engine intake; but also in the bypass duct or in the outlet some liners can be found. Despite the decrease of overall engine noise due to the increase of bypass-ratio (BPR), cut-off design for rotor-stator combinations, and various other means, there is an increasing demand for efficient broad-band noise absorption with the final goal of further overall noise reduction. This demand is mainly caused through the reduction of the dominating tonal components, but might be also connected to an increase in broadband noise itself. In addition, the increase in BPR requires shorter nacelles in order to reduce associated drag and weight penalties. This leads not necessarily to a smaller area for liner installation e.g. in the intake of the engine, but to a shorter length of the intake and thereby to a shorter propagation distance of emitted noise over a lined surface in axial direction. State of the art for inlet liners are singleand double-degree of freedom (SDOF and DDOF) liners consisting of cells of fixed size (for DDOF for instance with a septum dividing the individual cells) covered with a perforated face sheet, and a rigid back plate. The whole liner structure must be very robust, but at the same time of light weight, withstand various fluids and environmental conditions etc. Current liners are","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"94 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132018340","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of an Improved Core Noise Prediction Method for Long-cowl Engines","authors":"Celia M. Ekoule, B. Tester, S. Funke, C. Richter","doi":"10.2514/6.2018-4090","DOIUrl":"https://doi.org/10.2514/6.2018-4090","url":null,"abstract":"This paper describes the process of developing an improved method to predict the core noise radiated by long-cowl engines under static and flight conditions. The proposed method follows the same approach as the industry standard SAE ARP 876 method in terms of structure and source model, but uses: (1) a new, analytical frequency-dependent directivity accounting for radiation, convection and refraction effects through the jet and (2) a new empirical source spectrum determined using a source breakdown code applied to external phased array data acquired on a Rolls-Royce BR700-type engine.","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"14 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130857461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aerofoil Surface Pressure Reconstruction from Far-Field Array Measurements","authors":"F. C. Hirono, P. Joseph, F. Fazi","doi":"10.2514/6.2018-3135","DOIUrl":"https://doi.org/10.2514/6.2018-3135","url":null,"abstract":"This paper covers the relationship between the far-field sound radiation of an aerofoil interacting with a turbulent flow and the Spatial Fourier Transform of the dipole source strength distribution over the aerofoil surface. It is shown that each far-field microphone effectively samples the source wavenumber spectrum at a particular wavenumber associated with the observer position and the Mach number; these wavenumbers are inside the “acoustic domain” in the wavenumber space and correspond to propagating plane waves, while wavenumbers outside this domain correspond to evanescent waves and are not visible in the far-field. We briefly discuss the surface pressure properties of a flat plate aerofoil, where the flat plate response functions for supercritical and subcritical gusts are interpreted from a wavenumber-domain perspective and some examples of aerofoil surface pressure wavenumber power spectra are shown. We then propose a source estimation method from far-field measurements in a convected medium: this is based on the Inverse Spatial Fourier Transform of the sampled source wavenumber spectrum within the “acoustic domain”. Wavenumbers outside this domain are not recoverable from far-field observations; hence, the estimated source distribution contains only components that are efficient radiators of far-field sound, but is spatially bandlimited.","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131135264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Investigation of the Very Near Pressure Field of a Heated Supersonic Jet with a Total Temperature Non-Uniformity","authors":"K. Daniel, D. Mayo, Todd Lowe, W. Ng","doi":"10.2514/6.2018-3145","DOIUrl":"https://doi.org/10.2514/6.2018-3145","url":null,"abstract":"","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133067827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An Attempt to Reduce Airfoil Tonal Noise Using Fluid-Structure Interaction","authors":"Di Wu, G. Lam, R. Leung","doi":"10.2514/6.2018-3790","DOIUrl":"https://doi.org/10.2514/6.2018-3790","url":null,"abstract":"","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"297 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133286977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Prediction of Noise from Turbulent Boundary Layers Attached to Porous Media","authors":"Elisha R. Pager, Steven A. E. Miller","doi":"10.2514/6.2018-3297","DOIUrl":"https://doi.org/10.2514/6.2018-3297","url":null,"abstract":"Aerospace vehicles, wind tunnel test section walls, and other structures often contain porosity that alters the turbulent boundary layer and radiated noise. A semi-empirical mathematical model is developed to predict and analyze the acoustic radiation from turbulent boundary layers over porous media. The model is an acoustic analogy that depends on local flow-field statistics. These statistics are calculated through a steady Reynoldsaveraged Navier-Stokes computational fluid dynamics solver that includes porous material. Acoustic predictions are conducted for four subsonic Mach numbers without a pressure gradient. At each Mach number, four porosities with constant liner depth and porous turbulent length scale are examined along with the non-porous solution. The flow-field is validated through comparison with acoustic measurement. Predictions are conducted to ascertain changes in acoustic radiation with varying porosity. We find that noise is amplified or reduced in a non-intuitive way with the introduction of porosity, variation of frequency, and increase of Mach number.","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127614534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SWAHILI: an experimental aerodynamic and acoustic database of a 2D high lift wing with sweep angle and flap side edge","authors":"E. Manoha, R. Davy, M. Pott-Pollenske, S. Barré","doi":"10.2514/6.2018-3459","DOIUrl":"https://doi.org/10.2514/6.2018-3459","url":null,"abstract":"","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124575170","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Trailing-edge noise of a flat plate with several liner-type porous appendices","authors":"S. Moreau, Bastien Dignou, Prateek Jaiswal, G. Yakhina, Y. Pasco, M. Sanjosé, B. Alstrom, N. Atalla","doi":"10.2514/6.2018-3119","DOIUrl":"https://doi.org/10.2514/6.2018-3119","url":null,"abstract":"","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"7 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114463291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Aeroacoustic and Aerodynamic Analysis of a Large-scale Flap Side-edge Model","authors":"Daniel Acevedo Giraldo, F. Catalano","doi":"10.11606/D.18.2019.TDE-09092019-183442","DOIUrl":"https://doi.org/10.11606/D.18.2019.TDE-09092019-183442","url":null,"abstract":"ACEVEDO, G. D. Experimental Aeroacoustic and Aerodynamic Analysis of a Large-Scale Flap Side-Edge Model. 2019. 142p. Dissertation (Master of Science) São Carlos School of Engineering, University of São Paulo, São Carlos, 2019. The first bypass turbofan engines came into operation in the early 1970’s. The need for reductions in the fuel consumption affected aircraft noise positively through reductions in the jet noise. Over the past decades, the bypass ratio of turbofan engines has continuously increased and, as a result, aircraft engine noise has decreased to a level comparable to the noise originated from the turbulent flow around the airframe for take-off and landing conditions. Although aircraft have become quieter, the number of individuals affected by the aviation growth is likely to increase. Airframe noise has been currently identified as the ultimate aircraft noise barrier and many efforts devoted to its reductions have focused specifically on landing gears and high-lift devices, which are the most relevant noise contributors. Some devices have been designed to reduce flap noise, however, not all of them have been successfully tested in a detailed large-scale flap model due to their difficult implementation in real flap side-edges. This research investigates the relationship between the parameters of a large-scale flap model at 1.50× 106 Reynolds number and the physics responsible for flap side-edge noise generation, one of the most dominant sources of the airframe noise. Experimental tests were conducted in a wind-tunnel and flow-field measurements were taken by a multi-hole pitot probe and an aerodynamic balance and complemented by phased microphone array techniques towards a deeper understanding of flap side-edge noise sources and their correlations to unsteady vorticity fluctuations. Conventional beamforming and CLEAN-SC and DAMAS deconvolution methodologies provided far-field acoustic spectra estimations and noise source mapping. The model used for the tests consists of an unswept isolated flap element with representative tip details present in conventional medium-range transport aircraft. The instrumentation includes 106 steady pressure taps distributed chord-wise and span-wise and a sand trip tape to transition the laminar boundary layer. Different side-edge devices were assessed towards airframe noise reductions. A perforated side-edge treatment was also applied to the flap side-edge. Results of aerodynamic and aeroacoustic tests conducted in the LAE-1 closed circuit wind tunnel with a closed test section at the São Carlos School of Engineering University of São Paulo (EESC-USP) at up to 40 m/s flow speeds provided specific information on the aeroacoustic and aerodynamic characterization of the dominant acoustic source mechanisms of the flap model.","PeriodicalId":429337,"journal":{"name":"2018 AIAA/CEAS Aeroacoustics Conference","volume":"24 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-06-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114472925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}