Дисертації з теми "Wind tunnel noise"
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Stoker, Robert W. "A method to separate wind-tunnel background noise and wind noise from interior measurements." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/12032.
Повний текст джерелаGrant, Justin Alexander. "Far-field noise from a rotor in a wind tunnel." Thesis, Florida Atlantic University, 2016. http://pqdtopen.proquest.com/#viewpdf?dispub=10154927.
Повний текст джерелаThis project is intended to demonstrate the current state of knowledge in the prediction of the tonal and broadband noise radiation from a Sevik rotor. The rotor measurements were made at the Virginia Tech Stability Wind Tunnel. Details of the rotor noise and flow measurements were presented by Wisda et al(2014) and Murray et al(2015) respectively. This study presents predictions based on an approach detailed by Glegg et al(2015) for the broadband noise generated by a rotor in an inhomogeneous flow, and compares them to measured noise radiated from the rotor at prescribed observer locations. Discrepancies between the measurements and predictions led to comprehensive study of the flow in the wind tunnel and the discovery of a vortex upstream of the rotor at low advance ratios. The study presents results of RANS simulations. The static pressure and velocity profile in the domain near the rotor’s tip gap region were compared to measurements obtained from a pressure port array and a PIV visualization of the rotor in the wind tunnel
Griffith, Dwaine O. "Turbulence measurements and noise generation in a transonic cryogenic wind tunnel." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/45979.
Повний текст джерелаA high-frequency combination probe was used to measure dynamic flow quality in the test section of the NASA Langley 0.3-m Transonic Cryogenic Tunnel. The probe measures fluctuating stagnation (total) temperature and pressure, static pressure, and flow angles in two orthogonal planes. Simultaneous unsteady temperature and pressure measurements were also made in the settling chamber of the tunnel. The data show that the stagnation temperature fluctuations remain constant, and the stagnation pressure fluctuations increase by a factor of two, as the flow accelerates from the settling chamber to the test section. In the test section, the maximum rms value of the normalized fluctuating velocity is 0.7 percent. Correlation coefficients l failed to show vortlcity, entropy, or sound as the dominant mode of turbulence in the tunnel.
At certain tunnel operating conditions, periodic disturbances are seen in the data taken in the test section. A possible cause for the disturbances is found to be acoustic coupling of the test section and plenum chamber via the perforated side walls in the tunnel. The experimental data agree well with the acoustic coupling theory.
Master of Science
Owens, David Elliot. "Wall Features of Wing-Body Junctions: Towards Noise Reduction." Thesis, Virginia Tech, 2013. http://hdl.handle.net/10919/23717.
Повний текст джерелаMaster of Science
Schilden, Thomas [Verfasser]. "Numerical Analysis of Wind Tunnel Noise Decomposition Methods in Supersonic Flow / Thomas Schilden." München : Verlag Dr. Hut, 2019. http://d-nb.info/1181514126/34.
Повний текст джерелаRemillieux, Marcel Christophe. "Aeroacoustic Study of a Model-Scale Landing Gear in a Semi-Anechoic Wind Tunnel." Thesis, Virginia Tech, 2007. http://hdl.handle.net/10919/31674.
Повний текст джерелаMaster of Science
Spalt, Taylor B. "Background Noise Reduction in Wind Tunnels using Adaptive Noise Cancellation and Cepstral Echo Removal Techniques for Microphone Array Applications." Thesis, Virginia Tech, 2010. http://hdl.handle.net/10919/34247.
Повний текст джерелаMaster of Science
Wisda, David Martin. "Noise from a Rotor Ingesting Inhomogeneous Turbulence." Thesis, Virginia Tech, 2015. http://hdl.handle.net/10919/52986.
Повний текст джерелаMaster of Science
Yakhina, Gyuzel. "Experimental study of the tonal trailing-edge noise generated by low-reynolds number airfoils and comparison with numerical simulations." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEC008/document.
Повний текст джерелаThe tonal trailing-edge noise generated by transitional airfoils is a topic of interest because of its wide area of applications. One of them is the Unmanned Air Vehicles operated at low Reynolds numbers which are widely used in our everyday life and have a lot of perspectives in future. The tonal noise reduction will increase the survivability and effectiveness of the devices in military field. Moreover it will enlarge the range of civil use and minimize noise pollution. The effective noise reduction is needed and therefore the complete understanding of the tonal noise generation process is necessary. Despite the fact that investigation of the trailing-edge noise was started since the seventies there are still a lot of details which should be explained. The present work is dedicated to the experimental and analytical investigation of the tonal noise and is a part of the collaboration project between Ecole Centrale de Lyon and Embry-Riddle Aerospace University. The aim is to conduct an exhaustive experimental characterization of the acoustic and aerodynamic parameters of the trailing-edge noise and to produce a data base which can be used for further numerical simulations conducted at Embry-Riddle Aerospace University. A symmetric NACA-0012 airfoil and a slightly cambered SD7003 airfoil at moderate angles of attack (varied from -10° à 10°) were tested in an open-jet anechoic wind tunnel of Ecole Centrale de Lyon at moderate Reynolds numbers (0.6x105 < Rec < 2.6x105). Measurements of the wall pressure and far-field acoustic pressure in different configurations allowed to observe the ladder-type structure of the noise signature, to determine which side produced tones and to distinguish the role of the acoustic feedback loop. Additional post-processing techniques such as time-frequency analysis showed the existence of several regimes (switching regime between two tones, one-tone regime and multiple-tones regime) of noise emission. The bicoherence analysis showed that there are non-linear relationships between tones. The investigation of the role of the separation area by hot-wire anemometry and flow visualization techniques showed that the separation bubble is a necessary but not a suficient condition for the noise generation. Moreover the location of the bubble is also important and should be close enough to the trailing edge. Furthermore the linear stability analysis of accompanying numerical simulation results showed that the Tollmien-Schlichting waves transform to the Kelvin-Helmholtz waves at the separation area. An analytical prediction of the tone levels in the far-field was done using Amiet's model based on the assumption of perfectly correlated sources along the span. The wall-pressure measurements close to the trailing edge were used as an input data. The comparisons of the predicted levels and measured ones showed a good agreement. After analysis of all results the following description of the tonal noise mechanism is proposed. At some initial point of the airfoil the Tollmien-Schlichting instabilities start. They are traveling downstream and continued to Kelvin-Helmholtz waves along the shear-layer of the separation bubble. These waves reach the trailing edge, scatter from it as acoustic waves, which move upstream. The acoustic waves amplify the boundary layer instabilities at some frequencies for which the phases of both motions match and creates the feedback loop needed to sustain the process
Lemoine, Benoît. "Etude aéroacoustique de configurations génériques de dispositifs hypersustentateurs : approches analytique et expérimentale." Phd thesis, Ecole Centrale de Lyon, 2013. http://tel.archives-ouvertes.fr/tel-00965211.
Повний текст джерелаMurray, Henry Hall IV. "Turbulence and Sound Generated by a Rotor Operating Near a Wall." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71332.
Повний текст джерелаMaster of Science
Zumu, Doli Christian. "Transmission des fluctuations de bruit aéroacoustique dans un modèle d’habitacle automobile générées par un écoulement instationnaire : étude en soufflerie." Thesis, Poitiers, 2018. http://www.theses.fr/2018POIT2317/document.
Повний текст джерелаThis study aims at characterizing in a wind tunnel the aerodynamic mechanisms contributing to the generation and transmission of the noise fluctuations into a car interior model. The test bench designed in anechoic wind tunnel consists of a flow whose incoming flow velocity is modulated by a mobile flap, and which by interaction with a forward-facing step radiates an aeroacoustic noise transmitted through a glass into an anechoic box. The adopted approach consists, during the flap handling time, in measuring and connecting the external velocity field measured using the Time-Resolved laser Particle Image Velocimetry technique (TR-PIV at sampling frequency 20 kHz) to the wall pressure on the one hand, and then to the internal acoustic field obtained by transmission on the other hand. Spatio-temporal correlation tools are then used to highlight the flow areas that are the most correlated with the energy fluctuations of the wall pressure and with those of the internal noise level. The fluctuation of the aerodynamic loading of the window under the recirculation bubble is logically related to the unsteady activity of the latter, then further downstream to the vortex stream. As for the noise transmitted into the cabin model, it seems mainly related to the speed fluctuations in the shear layer. Finally, a specific procedure allows to evaluate the quasi-steady nature of the temporal variations of the fluctuating quantities, as well as the acoustic response of the window
Ferret, Bernard. "Etude expérimentale de l'intéraction entre un tourbillon isolé et un profil d'aile." Poitiers, 1988. http://www.theses.fr/1988POIT2317.
Повний текст джерелаStucki, Chad Lamar. "Aerodynamic Design Optimization of a Locomotive Nose Fairing for Reducing Drag." BYU ScholarsArchive, 2019. https://scholarsarchive.byu.edu/etd/7478.
Повний текст джерелаKuester, Matthew. "Acoustics in the Klebanoff-Saric Wind Tunnel: Background Identification, Forcing, and Active Control." Thesis, 2012. http://hdl.handle.net/1969.1/ETD-TAMU-2012-05-10731.
Повний текст джерелаMair, Robert S. "Wind tunnel drag evaluation of helicopter nose sections." Thesis, 1985. http://hdl.handle.net/10945/21626.
Повний текст джерела