Download or read book Comparison of Techniques to Measure the Low Wavenumber Wall Pressure Spectrum of a Turbulent Boundary Layer written by Kyle F. Martini and published by . This book was released on 1984 with total page 280 pages. Available in PDF, EPUB and Kindle. Book excerpt: The agreement between low wavenumber measurements of the turbulent wall pressure spectrum by various investigators has not been too good. Different techniques have been used in different facilities and have yielded data in different nondimensional frequency and wavenumber ranges. The current measurement program has utilized the wavenumber filtering techniques used by three primary investigators, the Martin plate, the Jameson plate and the Farabee and Geib 6-element microphone array in the same facility. Also a 12-element collinear and stagger array and a lateral array were used. The agreement between the different techniques in the M.I.T. facility is generally good. In addition, the difference of results between facilities has been reduced by displaying the data in a non-dimensional form that does not include the effect of boundary layer thickness. However, there was still a significant scatter in the data for each technique. Scatter is believed to be due to variation of each filter's wavenumber response away from the main acceptance lobe where the filter is responding to the acoustic and convective contamination and also the variation of the contamination with flow speed.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Direct Measurements of Turbulent Boundary Layer Wall Pressure Wavenumber frequency Spectra on Smooth and Riblet coated Plates written by Bruce M. Abraham and published by . This book was released on 2000 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Low wavenumber Content of the Spectrum of the Wall Pressure Under a Turbulent Boundary Layer written by K. L. Chandiramani and published by . This book was released on 1968 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: The report deals with the low-wavenumber content of the wall-pressure spectrum under a turbulent boundary layer. A discussion is given of the importance of the low-wavenumber content for evaluating transducer attenuation. Comments are made on the lack of reliable experimental data regarding the low-wavenumber content. Calculations are presented to substantiate the above comments. Direct experimental measurements of the low-wavenumber content are reported. (Author).

Download or read book Advances in Fluid Mechanics Measurements written by MOHAMED GAD-EL-HAK and published by Springer Science & Business Media. This book was released on 2013-03-08 with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt: One cannot overemphasize the importance of studying fluids in motion or at rest for a variety of scientific and engineering endeavors. Fluid mechanics as an art reaches back into antiquity, but its rational formulation is a relatively recent undertaking. Much of the physics of a particular flow situation can be understood by conducting appropriate experiments. Flow visualization techniques offer a useful tool to establish an overall picture of a flow field and to delineate broadly its salient features before embarking on more detailed quantitative measurements. Among the single-point measurements that are particularly difficult are those in separated flows, non-Newtonian fluids, rotating flows, and nuclear aerosols. Pressure, shear stress, vorticity, and heat transfer coefficient are also difficult quantities to measure, particularly for time-dependent flows. These and other special situations are among the topics covered in this volume. Each article emphasizes the development of a particular measuring technique. The topics covered were chosen because of their importance to the field, recent appeal, and potential for future development. The articles are comprehensive and coverage is pedagogical with a bias towards recent developments.

Download or read book Mechanics of Flow Induced Sound and Vibration Volume 2 written by William K. Blake and published by Academic Press. This book was released on 2017-08-14 with total page 696 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanics of Flow-Induced Sound and Vibration, Volume 2: Complex Flow-Structure Interactions, Second Edition, enables readers to fully understand flow-induced vibration and sound, unifying the disciplines of fluid dynamics, structural dynamics, vibration, acoustics, and statistics in order to classify and examine each of the leading sources of vibration and sound induced by various types of fluid motion. Starting from classical theories of aeroacoustics and hydroacoustics, a formalism of integral solutions valid for sources near boundaries is developed and then broadened to address different source types, including hydrodynamically induced cavitation and bubble noise, turbulent wall-pressure fluctuations, pipe and duct systems, lifting surface flow noise and vibration, and noise from rotating machinery. Each chapter is illustrated with comparisons of leading formulas and measured data. Combined with its companion book, Mechanics of Flow-Induced Sound and Vibration, Volume 1: General Concepts and Elementary Sources, the book covers everything an engineer needs to understand flow-induced sound and vibration. This book will be a vital source of information for postgraduate students, engineers and researchers with an interest in aerospace, ships and submarines, offshore structures, construction, and ventilation. Presents every important topic in flow-induced sound and vibration Covers all aspects of the topics addressed, from fundamental theory, to the analytical formulas used in practice Provides the building blocks of computer modeling for flow-induced sound and vibration

Download or read book Mechanics of Flow Induced Sound and Vibration V2 written by William K. Blake and published by Elsevier. This book was released on 2012-12-02 with total page 569 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mechanics of Flow-Induced Sound and Vibration V2

Download or read book Masters Theses in the Pure and Applied Sciences written by Wade H. Shafer and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 407 pages. Available in PDF, EPUB and Kindle. Book excerpt: Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Data Analysis and Synthesis (CINDAS) * at Purdue University in 1 957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 29 (thesis year 1984) a total of 12,637 theses titles from 23 Canadian and 202 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 29 reports theses submitted in 1984, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.

Download or read book Low Wavenumber Levels of Turbulent Boundary Layer Wall Pressure Fluctuations in Zero and Adverse Gradients written by Mark Jay Moeller and published by . This book was released on 1978 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: The low wavenumber components of the turbulent boundary layer wavenumber frequency spectrum of wall pressure fluctuations were measured with two flush-mounted rectangular plates having approximately clamped boundary conditions. The plates were designed to provide low wavenumber measurements at higher frequencies and wavenumbers than previous plate experiments in order to provide data comparable with measurements made by Farabee and Geib (7) with an array of flush-mounted microphones. The low wavenumber measurements were made in the M.I.T. low noise low turbulence subsonic wind tunnel under zero and adverse pressure gradient conditions. When nondimensionalized on outer boundary layer variables the adverse pressure gradient data do not exhibit increased levels from those of the zero pressure gradient data. The zero pressure gradient data are in good agreement with the levels reported by Farabeen and Geib (7) for the same nondimensional frequency and wavenumber range. (Author).

Download or read book Wavenumber Spectral Measurement of Turbulent Boundary Layer Wall Pressure by Maximum Likelihood Methods written by P. S. Tong and published by . This book was released on 1979 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combined procedure based on conventional and maximum likelihood spectral estimation techniques is proposed for the measurement of turbulent boundary layer pressure fluctuation wavenumber spectrum. It is shown that the mixed procedure is more tolerant to sensor inaccuracies in amplitude, phase or phase center alignment. (Author).

Download or read book Sensitivity to Mean Flow Parameters of the Low Wavenumber Content of the Wall Pressure Under a Turbulent Boundary Layer written by J. E Cole (III.) and published by . This book was released on 1985 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objective of this study is to examine the sensitivity of the low wavenumber portion of the wall pressure field under a turbulent boundary layer to both flow and wall conditions. The analytical procedure makes use of a method for calculating the broadband correlation function of the wall pressure field in which the specific flow characteristics enter through profiles of the mean velocity shear and turbulence intensity across the boundary layer. The basic assumption used to extend the results of this procedure to narrowband frequency characteristics is that there is a range of large spatial separations in which Strouhal scaling is not important. Several specific boundary layers are considered including flows on smooth and rough walls and in zero, favorable, and adverse pressure gradients. Results are presented for the point pressure, the spatial correlation function, and the low wavenumber spectral level. Keywords: GHR(General Hydromechanics Research) program; Wall pressure fluctuations; Low Wavenumber.

Download or read book Turbulent Boundary Layer Models for Acoustic Analysis written by Teresa S. Miller and published by . This book was released on 2011 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis of the three types of turbulent boundary layer (TBL) models for acoustic analysis is presented because current preferred models over-predict TBL contributions to aircraft interior noise predictions. The mean square pressure is a measure of the total energy due to the pressure fluctuations beneath a turbulent boundary layer. The single point wall pressure spectrum sorts the energy into frequencies. The normalized wavenumber-frequency spectrum sorts the energy into wavenumbers. The pressure fluctuations beneath a turbulent boundary layer are found by solving the Poisson equation. In this work, the Poisson equation is solved both numerically and analytically using data from an LES/DES simulation. The numerical solution uses the point Gauss-Seidel method and has reasonable results. The analytical solution uses an eigenvalue expansion method that is less successful. The empirical mean square pressure models predict a relatively large spread in the pressure fluctuation values. It is difficult to draw any meaningful conclusions on which mean square pressure model is preferred when compared to data from the Spirit AeroSystems 6x6 duct. The single point wall pressure spectrum models are evaluated and the two more modern models of Smol'yakov and Goody seem to perform the best. These models are also compared to data from the Spirit AeroSystems 6x6 duct. The spectrum at low frequencies rolled off similar to the Goody model. This analysis indicates that the Goody model is the appropriate single point wall pressure spectrum model for aircraft applications. Important features of the normalized wavenumber-frequency spectrum models are presented and can be classified as either separable or non-separable. Separable models in the Corcos normalized wavenumber-frequency spectrum model class tend to over-predict the response for a range of cases. Both the non-separable Chase 1 and Smol'yakov-Tkachenko models appear to match the M.I.T. low noise, low turbulence wind tunnel data throughout the range of comparison. The Smol'yakov-Tkachenko model does not lend itself to straight forward Fourier transforms needed by the acoustic models. But the Chase 1 model can be converted from wavenumber-frequency spectrum to the cross spectrum, so it is the preferred model for aircraft applications. Therefore, the preferred turbulent boundary layer models for aircraft interior noise predictions are the single point wall pressure spectrum model of Goody and the normalized wavenumber-frequency spectrum model of Chase 1.

Download or read book Low Wavenumber Turbulent Boundary Layer Wall Pressure and Shear Stress Measurements from Vibration Data on a Cylinder in Pipe Flow written by William K. Bonness and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Low wavenumber Turbulent Boundary Layer Wall pressure Measurements from Vibration Data Over Smooth and Rough Surfaces in Pipe Flow written by Neal D. Evans and published by . This book was released on 2011 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1970 with total page 796 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Low wavenumber Content of the Spectrum of the Wall Pressure Under a Turblent Boundary Layer written by Bolt, Beranek, and Newman and published by . This book was released on 1968 with total page 60 pages. Available in PDF, EPUB and Kindle. Book excerpt: