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A Visual Study Of The Structure Of Turbulent Cyclonic Boundary Layers And The Effects Of Turbulence Suppression Techniques
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Book Synopsis A Visual Study of the Structure of Turbulent Cyclonic Boundary Layers and the Effects of Turbulence Suppression Techniques by : Melody Lynne Munson-McGee
Download or read book A Visual Study of the Structure of Turbulent Cyclonic Boundary Layers and the Effects of Turbulence Suppression Techniques written by Melody Lynne Munson-McGee and published by . This book was released on 1985 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis A Study of Turbulent Boundary Layer Structure by : John Leask Lumley
Download or read book A Study of Turbulent Boundary Layer Structure written by John Leask Lumley and published by . This book was released on 1986 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Structure of Turbulent Boundary Layers and Shock Wave Boundary Layer Interactions by :
Download or read book The Structure of Turbulent Boundary Layers and Shock Wave Boundary Layer Interactions written by and published by . This book was released on 1993 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: This report is the Final Technical Report for AFOSR Grant 89-0420, monitored by Dr James McMichael, for the period June 15, 1989 to October 14, 1992. Under this program, research was performed (1) to describe the structure of the large-scale motions in supersonic turbulent boundary layers, (2) to study the interaction of that turbulence with shock waves and strategies for controlling the interaction, (3) to differentiate between Mach and Reynolds number effects on turbulence structure in wall-bounded flows, and (4) to develop and implement new non-intrusive diagnostic techniques. The research is aimed at providing physical insight, and scaling information, for the development of turbulence models appropriate for supersonic shear layers. The primary experimental means used in these investigations were the Rayleigh scattering technique to study the instantaneous density field, the RELIEF line tagging method to study the instantaneous velocity field, and a dual hot-wire technique to obtain simultaneous velocity and density signals ... Boundary layers, Turbulence, Shock wave boundary layer interaction.
Book Synopsis Analysis of Turbulent Boundary Layers by : Tuncer Cebeci
Download or read book Analysis of Turbulent Boundary Layers written by Tuncer Cebeci and published by Elsevier. This book was released on 2012-12-02 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: Analysis of Turbulent Boundary Layers focuses on turbulent flows meeting the requirements for the boundary-layer or thin-shear-layer approximations. Its approach is devising relatively fundamental, and often subtle, empirical engineering correlations, which are then introduced into various forms of describing equations for final solution. After introducing the topic on turbulence, the book examines the conservation equations for compressible turbulent flows, boundary-layer equations, and general behavior of turbulent boundary layers. The latter chapters describe the CS method for calculating two-dimensional and axisymmetric laminar and turbulent boundary layers. This book will be useful to readers who have advanced knowledge in fluid mechanics, especially to engineers who study the important problems of design.
Book Synopsis The Effects of Streamwise Concave Curvature on Turbulent Boundary Layer Structure by : Albert H. Jeans
Download or read book The Effects of Streamwise Concave Curvature on Turbulent Boundary Layer Structure written by Albert H. Jeans and published by . This book was released on 1982 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Concave curvature has a relatively large, unpredictable effect on turbulent boundary layers. Some, but not all previous studies suggest that a large-scale, stationary array of counter-rotating vortices exists within the turbulent boundary layer on a concave wall. The objective of the present study was to obtain a qualitative model of the flow field in order to increase our understanding of the underlying physics. A large free-surface water channel was constructed in order to perform a visual study of the flow. Streamwise components of mean velocity and turbulence intensity were measured using a hot film anemometer. The upstream boundary was spanwise uniform with a momentum thickness to radius of curvature of 0.05. Compared to flat wall flow, large-scale, randomly distributed sweeps and ejections were seen in the boundary layer on the concave wall. The sweeps appear to suppress the normal mechanism for turbulence production near the wall by inhibiting the bursting process. The ejections appear to enhance turbulence production in the outer layers as the low speed fluid convected from regions near the wall interacts with the higher speed fluid farther out. The large-scale structures did not occur at fixed spanwise locations, and could not be called roll cells or vortices. (Author).
Book Synopsis Workshop on Coherent Structure of Turbulent Boundary Layers by : C. R. Smith
Download or read book Workshop on Coherent Structure of Turbulent Boundary Layers written by C. R. Smith and published by . This book was released on 1978 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt: A discussion of the role of visual and probe measurements in turbulent structure research is given, stressing the constraining limitations of each and the interrelationships of the two methods. A selective history of the use of visual results is discussed in terms of the constraining limitations of the visual methods. Retrospective remarks are presented concerning the Stanford visual data on the inner portions of turbulent boundary layer structure. The final section discusses some general features of what is currently known about the structure of turbulent boundary layers, draws conclusions from this general knowledge, and poses questions that seem currently important in gaining further understanding. The paper stresses overall aspects of the structure problem at the expense of details in an attempt to gain perspective. (Author).
Book Synopsis Analyses of Turbulence in the Neutrally and Stably Stratified Planetary Boundary Layer by : Cedrick Ansorge
Download or read book Analyses of Turbulence in the Neutrally and Stably Stratified Planetary Boundary Layer written by Cedrick Ansorge and published by Springer. This book was released on 2016-09-15 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents a study of strong stratification and turbulence collapse in the planetary boundary layer, opening a new avenue in this field. It is the first work to study all regimes of stratified turbulence in a unified simulation framework without a break in the paradigms for representation of turbulence. To date, advances in our understanding and the parameterization of turbulence in the stable boundary layer have been hampered by difficulties simulating the strongly stratified regime, and the analysis has primarily been based on field measurements. The content presented here changes that paradigm by demonstrating the ability of direct numerical simulation to address this problem, and by doing so to remove the uncertainty of turbulence models from the analysis. Employing a stably stratified Ekman layer as a simplified physical model of the stable boundary layer, the three stratification regimes observed in nature— weakly, intermediately and strongly stratified—are reproduced, and the data is subsequently used to answer key, long-standing questions. The main part of the book is organized in three sections, namely a comprehensive introduction, numerics, and physics. The thesis ends with a clear and concise conclusion that distills specific implications for the study of the stable boundary layer. This structure emphasizes the physical results, but at the same time gives relevance to the technical aspects of numerical schemes and post-processing tools. The selection of the relevant literature during the introduction, and its use along the work appropriately combines literature from two research communities: fluid dynamics, and boundary-layer meteorology.
Book Synopsis Study of the Structure of Turbulence in Accelerating Transitional Boundary Layers by : Michael F. Blair
Download or read book Study of the Structure of Turbulence in Accelerating Transitional Boundary Layers written by Michael F. Blair and published by . This book was released on 1987 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: A combined experimental and analytical program has been conducted to examine transitional, accelerating boundary layer flows with high levels of freestream turbulence. An earlier program focused on measurement of transitional heat transfer distributions for four combinations of streamwise acceleration and freestream turbulence. The present program was designed to document the boundary layer turbulence structure and spectral distributions for the same four test conditions. The results from the present program have shown that transition in accelerating flows consists of an acceleration dominated stage of slowly developing intermittency followed by a second stage with the same general characteristics as zero-pressure-gradient transition. Conditionally sampled fluctuating velocity profile measurements indicated that the boundary layer turbulence was highly anisotropic in the early stages of transition. Conditionally sampled mean velocity measurements showed that within the intermittent turbulent patches the mean velocity profiles were very similar to those of an equilibrium turbulent boundary layer. Spectral distribution data indicated that preferred amplification of the most unstable (as predicted by linear stability theory) frequencies occurred upstream of the onset of transitional bursting. In addition to the experimental portion of this investigation, numerical experiments were undertaken to assess the ability of currently existing methods to predict heat transfer during transition in accelerating flows.
Book Synopsis Some Characteristics of Turbulent Boundary Layers in Rapidly Accelerated Flows by : Paul F. Brinich
Download or read book Some Characteristics of Turbulent Boundary Layers in Rapidly Accelerated Flows written by Paul F. Brinich and published by . This book was released on 1971 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: An analysis of time-mean-turbulent boundary layer velocity profiles measured in a rapidly accelerating flow suggests that the outer region of the velocity profiles consists of essentially inviscid, rotational flow. The extent of this inviscid outer region was observed in some cases to exceed 90 percent of what is ordinarily thought of as the turbulent boundary layer thickness. On the other hand, the inner frictional region of these velocity profiles appears to have turbulent characteristics similar to those of more conventional turbulent boundary layers. Hence, the outer edge boundary condition for this inner region is more properly the external rotational flow region than the free stream.
Book Synopsis Effect of Favourable Pressure Gradient on Turbulence in Boundary Layers by :
Download or read book Effect of Favourable Pressure Gradient on Turbulence in Boundary Layers written by and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis explores the effects of favourable pressure gradient on the structure of turbulent boundary layers (TBL). In this context, the structure of three types of boundary layers namely a zero-pressure-gradient boundary layer, equilibrium boundary layers under favourable pressure gradient and relaminarising boundary layers is investigated mostly from the point of view of large-scale dynamics. This covers a whole range of flows on the so-called Reynolds number - pressure gradient diagram - from turbulent zero pressure gradient flows to relaminarising flows at relatively low Reynolds numbers. The study of turbulent and relaminarising boundary layers is carried out primarily using direct numerical analyses and some limited experiments in this thesis. The direct numerical simulations (DNS) of a zero-pressure-gradient turbulent boundary layer (ZPG TBL) is validated against the experimental and DNS data available in the literature. Furthermore, the important question of time-averaged signature of a large scale vortex structure and its relation with the two-point correlations in the context of ZPG TBL is addressed. In this context, a synthetic flow consisting of hairpin vortex structures is generated. The two-point correlations in the synthetic TBL and a real TBL are found to be qualitatively similar. This shows that the vortex structure leaves a time-averaged footprint in the form of correlations of velocity and vorticity. A study of two-point correlations in a real TBL shows that the structure angle deduced from two-point correlations varies with wall-normal location. The structure angle is small near the wall and increases away from the wall in agreement with the previous studies. The small angle close to the wall signifies the presence of streamwise structure. Away from the wall, this streamwise coherence is lost and the correlation contours become more isotropic. The presence of the wall and the mean shear affects smaller scales making them anisotropic close to th
Book Synopsis Scientific and Technical Aerospace Reports by :
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1992 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulence Nature and the Inverse Problem by : L. N. Pyatnitsky
Download or read book Turbulence Nature and the Inverse Problem written by L. N. Pyatnitsky and published by Springer Science & Business Media. This book was released on 2009-03-22 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrodynamic equations well describe averaged parameters of turbulent steady flows, at least in pipes where boundary conditions can be estimated. The equations might outline the parameters fluctuations as well, if entry conditions at current boundaries were known. This raises, in addition, the more comprehensive problem of the primary perturbation nature, noted by H.A. Lorentz, which still remains unsolved. Generally, any flow steadiness should be supported by pressure waves emitted by some external source, e.g. a piston or a receiver. The wave plane front in channels quickly takes convex configuration owing to Rayleigh's law of diffraction divergence. The Schlieren technique and pressure wave registration were employed to investigate the wave interaction with boundary layer, while reflecting from the channel wall. The reflection induces boundary-layer local separation and following pressure rapid increase within the perturbation zone. It propagates as an acoustic wave packet of spherical shape, bearing oscillations of hydrodynamic parameters. Superposition of such packets forms a spatio-temporal field of oscillations fading as 1/r. This implies a mechanism of the turbulence. Vorticity existing in the boundary layer does not penetrate in itself into potential main stream. But the wave leaving the boundary layer carries away some part of fluid along with frozen-in vorticity. The vorticity eddies form another field of oscillations fading as 1/r2. This implies a second mechanism of turbulence. Thereupon the oscillation spatio-temporal field and its randomization development are easy computed. Also, normal burning transition into detonation is explained, and the turbulence inverse problem is set and solved as applied to plasma channels created by laser Besselian beams.
Book Synopsis Large-Scale Streamwise Turbulent Structures in Hypersonic Boundary Layers by : Benjamin L. English
Download or read book Large-Scale Streamwise Turbulent Structures in Hypersonic Boundary Layers written by Benjamin L. English and published by . This book was released on 2013 with total page 96 pages. Available in PDF, EPUB and Kindle. Book excerpt: Prior research in the field of boundary layer turbulence has identified streamwise-elongated large-scale turbulence structures in both low speed compressible and high speed (M=2.0) flow. No experimental work has been done in any flow of M>̲3 in an attempt to identify the presence or quantify the behavior of these structures, nor has any study of favorable pressure gradient or surface roughness element effects on these structures been conducted. This research used high-resolution Particle Imaging Velocimetry in a M = 4.9 blow-down wind tunnel accompanied by a series of data analysis in order to identify the existence of streamwise-elongated large-scale turbulence structures in a hypersonic boundary layer. Furthermore, this study identified physical and statistical behavior which suggests that increasing favorable pressure gradient had a substantial impact on both the structural coherence and relative intensity of these turbulent structures at all boundary layer heights tested. This experiment also identified similar effects on these structures in the lower half of the boundary layer as a result of the introduction of surface roughness elements. Finally, several trends were identified between the averaged turbulence statistics and the behavior of the large-scale streamwise-elongated turbulence structures present in this study. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149550
Book Synopsis The Effects of Free-Stream Turbulence on the Turbulence Structure and Heat Transfer in Zero Pressure Gradient Boundary Layers by : M. F. Blair
Download or read book The Effects of Free-Stream Turbulence on the Turbulence Structure and Heat Transfer in Zero Pressure Gradient Boundary Layers written by M. F. Blair and published by . This book was released on 1982 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: In an earlier funded investigation, experimental research was conducted to deterine the influence of free-stream turbulence on turbulent boundary layer heat transfer and mean profile development. The data obtained under this earlier contract indicated that both the skin friction and the heat transfer increased significantly with increased free-stream turbulence level. Under the present investigation, detailed boundary layer turbulence structural data and turbulent heat transfer data were obtained for experimental test conditions and profile locations selected from the earlier test matrix. Numerious measurements assured that the present test conditions (boundary layer development and free-stream turbulence distributions) duplicated those of the earlier contract. The purposes for making these present detailed boundary layer turbulence measurements were: to provide data to which current finite-difference boundary layer turbulence models could be compared, and to generate a data base for the development of new analytical models for bondary layer heat transfer prediction. With the completion of the experimental portion of this investigation, a theoretical effort was made to assess the capability of a finite difference boundary layer computer program, ABLE (Analysis of the Boundary Layer Equations) for predicting the effect of free-stream turbulence on momentum and thermal boundary layers.
Book Synopsis A Compilation of Unsteady Turbulent Boundary Layer Experimental Data by : Lawrence W. Carr
Download or read book A Compilation of Unsteady Turbulent Boundary Layer Experimental Data written by Lawrence W. Carr and published by . This book was released on 1981 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive literature search was conducted and those experiments related to unsteady turbulent boundary-layer behavior were cataloged. In addition, an international survey of industrial, university, and government research laboratories was made, in which new and ongoing experimental programs associated with unsteady turbulent boundary-layer research were identified. Pertinent references were reviewed and classified based on the technical emphasis of the various experiments that include instantaneous or ensemble-averaged profiles of boundary-layer variables are stressed. Detailed reviews that include descriptions of the experimental apparatus, flow conditions, summaries of acquired data, and significant conclusions are made. The measurements made in these experiments that exist in digital form have been stored on magnetic tape, and instructions are presented for accessing these data sets for further analysis. (Author).
Book Synopsis Study of Unsteady Turbulent Boundary Layers by : Angel Nicolas Menendez
Download or read book Study of Unsteady Turbulent Boundary Layers written by Angel Nicolas Menendez and published by . This book was released on 1983 with total page 226 pages. Available in PDF, EPUB and Kindle. Book excerpt: A turbulent boundary layer, subjected to a free-stream velocity which changes sinusiodally in time under a zero time mean pressure gradient, is studied both experimentally and analytically. Using a two-component Laser Doppler Anemometer and a Heat Flux Gage, detailed and high quality information is obtained on the instantaneous velocity distribution and wall shear stress, respectively, at various stations. An asymptotic theory, for large Reynolds numbers, is developed for the oscillatory motion. It is valid for both boundary layers at arbitrary time-mean pressure gradients and fully developed pipe and channel flow, and is successfully applied to the present and previous available experimental information. The theory identifies two frequency parameters, in terms of which four different frequency regimes are defined. Similarity laws are identified for each one of these frequency regimes. All the experimental data have been archived on magnetic tape. (Author).
Book Synopsis Method for Predicting Compressible Turbulent Boundary Layers in Adverse Pressure Gradients by : Shimer Zane Pinckney
Download or read book Method for Predicting Compressible Turbulent Boundary Layers in Adverse Pressure Gradients written by Shimer Zane Pinckney and published by . This book was released on 1971 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt:
