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Author :
Publisher :
ISBN 13 :
Total Pages : 16 pages
Book Rating : 4.:/5 (317 download)
Download or read book Turbulent Wall-Pressure Fluctuations: New Model for Off-Axis Cross-Spectral Density written by and published by . This book was released on 1996 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Roberto Camussi
Publisher : Springer Science & Business Media
ISBN 13 : 3709114586
Total Pages : 453 pages
Book Rating : 4.7/5 (91 download)
Download or read book Noise Sources in Turbulent Shear Flows: Fundamentals and Applications written by Roberto Camussi and published by Springer Science & Business Media. This book was released on 2013-02-11 with total page 453 pages. Available in PDF, EPUB and Kindle. Book excerpt: The articles in this volume present the state-of-the-art in noise prediction, modeling and measurement. The articles are partially based on class notes provided during the course `Noise sources in turbulent shear flows', given at CISM on April 2011. The first part contains general concepts of aero acoustics, including vortex sound theory and acoustic analogies, in the second part particular emphasis is put into arguments of interest for engineers and relevant for aircraft design: jet noise, airfoil broadband noise, boundary layer noise (including interior noise and its control) and the concept of noise sources, their theoretical modeling and identification in turbulent lows. All these arguments are treated extensively with the inclusion of many practical examples and references to engineering applications.
Author : Elena Ciappi
Publisher : Springer Nature
ISBN 13 : 3030648079
Total Pages : 400 pages
Book Rating : 4.0/5 (36 download)
Download or read book Flinovia—Flow Induced Noise and Vibration Issues and Aspects-III written by Elena Ciappi and published by Springer Nature. This book was released on 2021-04-29 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume gathers the latest advances and innovations in the field of flow-induced vibration and noise, as presented by leading international researchers at the 3rd International Symposium on Flow Induced Noise and Vibration Issues and Aspects (FLINOVIA), which was held in Lyon, France, in September 2019. It explores topics such as turbulent boundary layer-induced vibration and noise, tonal noise, noise due to ingested turbulence, fluid-structure interaction problems, and noise control techniques. The authors’ backgrounds represent a mix of academia, government, and industry, and several papers include applications to important problems for underwater vehicles, aerospace structures and commercial transportation. The book offers a valuable reference guide for all those interested in measurement, modelling, simulation and reproduction of the flow excitation and flow induced structural response.
Author : Elena Ciappi
Publisher : Springer
ISBN 13 : 331909713X
Total Pages : 364 pages
Book Rating : 4.3/5 (19 download)
Download or read book Flinovia - Flow Induced Noise and Vibration Issues and Aspects written by Elena Ciappi and published by Springer. This book was released on 2014-11-23 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field. It describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation; for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays; for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements; for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses. This book presents the proceedings of the First International Workshop on Flow Induced Noise and Vibration (FLINOVIA), which was held in Rome, Italy, in November 2013. The authors’ backgrounds represent a mix of academia, government, and industry, and several papers include applications to important problems for underwater vehicles, aerospace structures and commercial transportation. The book offers a valuable reference guide for all those working in the area of flow-induced vibration and noise.
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Publisher :
ISBN 13 :
Total Pages : 804 pages
Book Rating : 4.:/5 (26 download)
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1971 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.F/5 ( download)
Download or read book NASA Technical Memorandum written by and published by . This book was released on 1997 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Howard Hubert Schloemer
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (227 download)
Download or read book Effects of Pressure Gradients on Turbulent Boundary-layer Wall-pressure Fluctuations written by Howard Hubert Schloemer and published by . This book was released on 1966 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The low-turbulence subsonic wind tunnel was significantly modified so that turbulent boundary-layer pressure fluctuation measurements could be made with adequate signal-to-noise ratio over a wide frequency range. Measurements were made in a mild adverse and a mild favorable pressure gradient with natural transition occurring in the boundary layer. To make certain that the facility was operating correctly and to establish a basis for comparison, the zero-pressure gradient case was investigated. For this case, the spectral density, magnitude of the normalized longitudinal and lateral cross-spectral density functions, and convection velocity as a function of longitudinal separation and frequency were in excellent agreement with other experimenters. When comparison is made to the zero-pressure gradient in the same non-dimensionalized frequency band and at similar non-dimensionalized longitudinal spacings, the convection velocity ratio is higher in the favorable and lower in the adverse pressure gradients, primarily due to the change in shape of the mean velocity profile. The effect of an adverse pressure gradient on the non-dimensionalized spectral density is to increase the low-frequency content without influencing the high-frequency portion appreciably, when compared to the zero-pressure gradient case. (Author).
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ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.:/5 (317 download)
Download or read book NASA Langley Scientific and Technical Information Output: 1996 written by and published by . This book was released on 1997 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 888 pages
Book Rating : 4.:/5 (318 download)
Download or read book Journal of Fluids Engineering written by and published by . This book was released on 1998 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 994 pages
Book Rating : 4.:/5 (31 download)
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 40 pages
Book Rating : 4.:/5 (317 download)
Download or read book Effect of Pressure Gradients on Plate Response and Radiation in a Supersonic Turbulent Boundary Layer written by and published by . This book was released on 1997 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : National Aeronautics and Space Administration (NASA)
Publisher : Createspace Independent Publishing Platform
ISBN 13 : 9781720629214
Total Pages : 88 pages
Book Rating : 4.6/5 (292 download)
Download or read book Modeling of Turbulent Boundary Layer Surface Pressure Fluctuation Auto and Cross Spectra - Verification and Adjustments Based on Tu-144ll Data written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-03 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: The literature on turbulent boundary layer pressure fluctuations provides several empirical models which were compared to the measured TU-144 data. The Efimtsov model showed the best agreement. Adjustments were made to improve its agreement further, consisting of the addition of a broad band peak in the mid frequencies, and a minor modification to the high frequency rolloff. The adjusted Efimtsov predicted and measured results are compared for both subsonic and supersonic flight conditions. Measurements in the forward and middle portions of the fuselage have better agreement with the model than those from the aft portion. For High Speed Civil Transport supersonic cruise, interior levels predicted by use of this model are expected to increase by 1-3 dB due to the adjustments to the Efimtsov model. The space-time cross-correlations and cross-spectra of the fluctuating surface pressure were also investigated. This analysis is an important ingredient in structural acoustic models of aircraft interior noise. Once again the measured data were compared to the predicted levels from the Efimtsov model.Rackl, Robert and Weston, AdamLangley Research CenterTU-144 AIRCRAFT; TURBULENT BOUNDARY LAYER; TUPOLEV AIRCRAFT; MATHEMATICAL MODELS; CIVIL AVIATION; PRESSURE; DATA PROCESSING; DATA REDUCTION; CROSS CORRELATION; AIRCRAFT NOISE; FLIGHT TESTS; POWER SPECTRA; FLIGHT ENVELOPES
Author : R. Ted Anderson
Publisher :
ISBN 13 :
Total Pages : 316 pages
Book Rating : 4.:/5 (844 download)
Download or read book Turbulent Wall Pressure Fluctuations in Terms of Spectral Densities Calculated from Discrete and Continuous Orr-Sommerfeld Eigenfunctions written by R. Ted Anderson and published by . This book was released on 1986 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Michael J. Allen
Publisher :
ISBN 13 :
Total Pages : 310 pages
Book Rating : 4.3/5 (91 download)
Download or read book Stochastic Analysis of Structural/acoustic Systems written by Michael J. Allen and published by . This book was released on 2001 with total page 310 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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ISBN 13 :
Total Pages : 78 pages
Book Rating : 4.:/5 (227 download)
Download or read book Calculation of Turbulent Boundary Layer Wall Pressure Spectra written by and published by . This book was released on 1993 with total page 78 pages. Available in PDF, EPUB and Kindle. Book excerpt: This study is an investigation into the suitability of various wavevector-frequency models of turbulent boundary layer wall pressure fluctuations for the prediction of experimental measurements of turbulent boundary layer wall pressure spectra. Three separate models of the wavevector- frequency spectrum proposed by D.M. Chase in 1980 and 1987 are evaluated. The wavevector-frequency spectral models are integrated numerically using a formulation for the point wall pressure spectrum (based on the work of Uberoi and Kovasznay). The representation of the wall pressure spectrum used accounts for the effect of a finite sized transducer on the measured wall pressure spectrum. By accounting for the area averaging effect of finite sized transducers on the measured turbulent boundary layer wall pressure spectra, it was possible to use Chase's rigorous formulations for the wavevector-frequency spectrum instead of the point pressure spectrum representations which assume an infinitely small measurement sensor. Results from the numerical integrations are compared to recent experimental data to determine which model of the wavevector- frequency spectrum most accurately predicts measured turbulent boundary layer wall pressure spectra. Data from experiments using fluids with a wide range of physical properties (air, water, and glycerine) are used for comparison purposes. Using the selected model, new empirical constants are established for use in the model for each fluid under consideration. Justification for use of the new empirical constants is given, and current limitations of the wavevector- frequency models are discussed.
Author : Miloud Alaoui
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (115 download)
Download or read book Coherent Structures and Wall-pressure Fluctuations Modeling in Turbulent Boundary Layers Subjected to Pressure Gradients written by Miloud Alaoui and published by . This book was released on 2016 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow around vehicles creates a turbulent boundary layer in the vicinity of the wall. The turbulent behavior induces pressure fluctuations that make the panels vibrate. These vibrations are then transmitted though the structure of the vehicle and radiate noise inside the cabin. The flow-induced noise levels increase with the speed of the vehicle. For this reason, aircraft manufacturers show a great interest in this topic.There are two objectives for this thesis: understand the mechanisms responsible for the wall-pressure fluctuations and predict this source of aircraft panel excitation.A study of available Large Eddy Simulation (LES) computations was performed. The database consists in simulations of turbulent boundary layer flows submitted to favorable, adverse and zero pressure gradients. This is necessary to understand the nature of the flow over curved geometries such as the aircraft flight deck. The effect of pressure gradients on coherent hairpin structures and hairpin packets could be identified and quantified based on visualization and statistical analysis methods. Linear stochastic estimation of the velocity fields revealed a pair of counter-rotating streamwise vortices above hairpin packets. These vortices have a vorticity opposite to that of the hairpins and an “inverse hairpin” model was proposed.Following the work of Ahn et al. (2010), a stochastic model for wall-pressure spectrum was developed. The idea is to build a stochastic turbulent velocity field using hairpin packets which are subjected to a mean flow. The characteristics of the packets depending on the pressure gradient are based on the analyses of the LES database. The pressure field at the wall is obtained by solving a Poisson equation. The results of the hairpin packet model are compared to numerical and experimental data. Finally, the model is used as input for a Statistical Energy Analysis (SEA) simulation in order to predict the levels of vibrations of panels submitted to a turbulent boundary layer flow over a portion of an aircraft cabin.
Author : David M. Chase
Publisher :
ISBN 13 :
Total Pages : 48 pages
Book Rating : 4.:/5 (227 download)
Download or read book Further Modeling of Turbulent Wall Pressure on a Cylinder and Its Scaling with Diameter written by David M. Chase and published by . This book was released on 1981 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The possible scaling of the axisymmetric component of spectral density of wall pressure in turbulent flow along a slender cylinder is reexamined with use of a formal low-wavenumber expansion in terms of fluctuating Reynolds stresses as sources. A rudimentary model of the sources is formed that conforms to the principle of local similarity near the wall and to probable implications of fluctuating and mean velocity profiles measured in cylindrical boundary layers. To the extent that wall pressure is exclusively due to such a turbulence field, to zero order in wavenumber, at least, it is indicated to scale with cylinder radius (a) and to agree in functional dependence with the current model for this low-wavenumber component. If the turbulence field (despite lack of experimental evidence) involves in addition a weak component that scales with boundary-layer thickness, then at sufficiently low frequencies and wavenumbers the corresponding contribution to wall pressure (when delta/a”1) may become dominant, and the extrapolation of the current model to very small omega a/U(Infinity) and the associated prediction of diameter dependence may then fail.
