Download or read book Effect of Local Surface Roughness on Turbulent Boundary Layer Wall Pressure Spectra and Transition Burst Onset written by Edmund J. O'Keefe and published by . This book was released on 1975 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of boundary-layer velocity profiles and turbulent wall-pressure spectra on a smooth flat plate with varying localized roughness conditions is reported. The sandpaper surface roughness ranged from a smooth wall to the fully rough condition. Transition and turbulent flow data are consistent with those in the published literature. In addition, new data have been obtained for the wall-pressure spectra for a complete range of roughness conditions. Formulas for estimating the increase in wall spectra levels due to varying surface-roughness conditions are presented.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1976 with total page 978 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 DTNSRDC written by David W. Taylor Naval Ship Research and Development Center and published by . This book was released on 1984 with total page 638 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 An Introductory Guide to EC Competition Law and Practice written by Valentine Korah and published by . This book was released on 1994 with total page 2354 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanics of Flow induced Sound and Vibration Complex flow structure interactions written by William K. Blake and published by . This book was released on 1986 with total page 584 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Influence of Surface Roughness on Supersonic High Reynolds Number Turbulent Boundary Layer Flow written by Robert M. Latin and published by . This book was released on 1998-03-01 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive study of rough-wall high speed (M=2.9) high Reynolds number (Re/m = 1.9. 10 to the 7th power) turbulent boundary layer flow was performed consisting of experimental, analytical, and numerical methods. Six wall topologies consisting of a smooth and five rough surfaces (two and three dimensional machined roughness plates; and 80, 36, and 20 grit sand-grain roughened plates) were studied. A confocal laser scan microscope was used to measure the topography of the sand grain roughnesses. The experimental measurement techniques included a convention Pitot pressure probe, laser Doppler velocimetry, hot wire anemometry; color schlieren and laser sheet Mie scattering images. Mean measurements included velocity, Mach number, density, and mass flux. Turbulent measurements included velocity and mass flux turbulence intensities, kinematic Reynolds shear stress, compressible Reynolds shear stress in two planes, and the traverse apparent mass flux. Kinematic turbulent flow statistical properties were found to scale by local mean quantities and displayed a weak dependence on surface roughness. Turbulent flow statistical properties with the explicit appearance of density did not scale by local mean quantities, and had a strong linear dependence on roughness. Surface roughness also had a significant effect on the flow structure size, angles, and energy spectra. A theoretical analysis was performed and a new integral method for the estimation of skin friction was developed. The skin friction estimates were within 4% of compressible semi-empirical relations. A numerical study was performed which used a parabolized Navier Stokes solver with two algebraic turbulence models and the Rotta model for surface roughness. A new method for the estimation of momentum loss improved the numerical flow predictability.
Download or read book Effect of Distributed Three dimensional Roughness and Surface Cooling on Boundary layer Transition and Lateral Spread of Turbulence at Supersonic Speeds written by Albert L. Braslow and published by . This book was released on 1959 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bursts and Pressure Fluctuations in Turbulent Boundary Layers written by Peter Bradshaw and published by . This book was released on 1986 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface pressure fluctuations below turbulent boundary layers were studied, in part, because they can be regarded as 'footprints' of passing turbulent eddies. The pressure fluctuations are formally described by a Poisson equation, implying that the pressure fluctuation at a given point is mathematically represented by the integral of a 'source' term over the whole flow field, with a weighting inversely proportional to the distance of the source from the given point. In turbulent boundary layers, fluctuations were made in a low-speed constant pressure the high-frequency part of the wall pressure fluctuations is generated mainly within the inner layer - say, the first 20% of the boundary layer thickness - and the low-frequency part is generated mainly in the outer layer. Measurements of velocity and surface-pressure turbulent boundary layer well downstream of an extensive region of wall roughness. The turbulence near the wall was representative of a smooth-wall flow, while that in the outer layer was typical of the upper stream rough-wall flow. Comparison with previous measurements on an entirely smooth wall illustrates the relative contributions of the inner and outer layers to the surface pressure fluctuations. Further work has been done to compare the VITA (Variable ge) conditional-sampling algorithm withuctuations were more advanced algorithms. Keywords: Turbulent boundary layer, Noise measurement, Statistical analysis, Surface roughness, and VITA algorithm.
Download or read book Aero hydroacoustics for Ships written by William K. Blake and published by . This book was released on 1984 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Effect of Controlled Surface Roughness on Boundary layer Transition and Heat Transfer at Mach Numbers of 4 8 and 6 0 written by Paul F. Holloway and published by . This book was released on 1964 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combined Irregular Roughness and Favorable pressure gradient Effects in a Turbulent Boundary Layer written by and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
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).
Download or read book Comparison of the Wall Pressure Fluctuations in Artificially Generated Turbulent Spots Natural Transition and Turbulent Boundary Layers written by Thomas S. Mautner and published by . This book was released on 1988 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments have been conducted to measure the wall pressure fluctuations associated with artificially generated turbulent spots in a laminar boundary layer. The results show that both the rms wall pressure and the wall pressure spectra of turbulent spots are influenced by the local mean flow pressure gradient. The zero and favorable pressure gradient wall pressure data are in agreement with turbulent boundary layer results. However, the current spot data shows that, in the presence of an adverse pressure gradient, the spot's rms wall pressure is approximately 1.5-2.5 times larger than that found for the zero and favorable pressure gradient cases. These results are in general agreement with the adverse pressure gradient data of Huang and Hannan (1975). Additionally, the nearly constant magnitude of the spot's adverse pressure gradient wall pressure spectrum indicates a nearly even distributions of energy with frequency. Keywords: Turbulent boundary layer, Laminar boundary layer, Wall pressure fluctuations.
Download or read book Effects of Specific Types of Surface Roughness on Boundary layer Transition written by Langley Aeronautical Laboratory and published by Hassell Street Press. This book was released on 2021-09-10 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important and is part of the knowledge base of civilization as we know it. This work is in the public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. To ensure a quality reading experience, this work has been proofread and republished using a format that seamlessly blends the original graphical elements with text in an easy-to-read typeface. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Download or read book Review of the Effect of Distributed Surface Roughness on Boundary layer Transition written by A. L. Braslow and published by . This book was released on 1960 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discussion is presented on the transition phenomena associated with distributed roughness, a correlation of three-dimensional roughness effects at both subsonic and supersonic speeds, and the effect of laminar boundary-layer stability as influenced by heat transfer, pressure gradients, and boundary-layer control on the sensitivity of laminar flow to distributed roughness. Results indicate that the transition-triggering mechanism of three-dimensionaltype surface roughness appears to be the same at supersonic and subsonic speeds. In either case, a Reynolds number based on the height of the roughness and the local flow conditions at the top of the roughness can be used to predict with reasonable accuracy the height of threedimensional roughness required to cause premature transition. Neither the three-dimensional roughness Reynolds number nor the lateral spread of turbulence behind the roughness is changed to any important extent by increasing the laminar boundary-layer stability to theoretically small disturbances. Therefore, for a given stream Mach number and Reynolds number, surface cooling, boundary-layer suction, or a favorable pressure gradient will, in the presence of three-dimensional roughness, promote rather than delay transition. (Author).
