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Author : Vincent Wilczynski
Publisher :
ISBN 13 :
Total Pages : 522 pages
Book Rating : 4.:/5 (269 download)
Download or read book Organized Turbulent Structures and Their Induced Wall Pressure Fluctuations written by Vincent Wilczynski and published by . This book was released on 1992 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Mark E. Kammeyer
Publisher :
ISBN 13 :
Total Pages : 314 pages
Book Rating : 4.:/5 (362 download)
Download or read book An Experimental Investigation of Organized Turbulent Motions and Wall-pressure Fluctuations in Complex Flows written by Mark E. Kammeyer and published by . This book was released on 1995 with total page 314 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 : John S. Serafini
Publisher :
ISBN 13 :
Total Pages : 88 pages
Book Rating : 4.:/5 (317 download)
Download or read book Wall-pressure Fluctuations and Pressure-velocity Correlations in a Turbulent Boundary Layer written by John S. Serafini and published by . This book was released on 1963 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: This experimental study was carried out at a free-stream Mach number of 0.6 and a Reynolds number per foot of 3.45 x 106. The magnitudes of the wall-pressure fluctuations agree with the Lilley-Hodgson theoretical results. Space-time correlations of the wall-pressure fluctuations generally agree with Willmarth's results for longitudinal separation distances. The convection velocity of the fluctuations is found to increase with increasing separation distances, and its significance is explained. Measurements with the longitudinal component of the velocity fluctuations indicate that the contributions to the wall-pressure fluctuations are from two regions, an inner region near the wall and an outer region linked with the intermittency.
Author : Steven J. Russell
Publisher :
ISBN 13 :
Total Pages : 195 pages
Book Rating : 4.:/5 (227 download)
Download or read book Wall Pressure Signatures of Organized Turbulent Motions written by Steven J. Russell and published by . This book was released on 1997 with total page 195 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extensive database of simultaneously obtained wall pressure and velocity measurements was acquired for a high Reynolds number, equilibrium turbulent flow. These data were obtained in both streamwise and spanwise measurement planes using an array of wall pressure transducers. Analyses of these data were performed to examine the spatial extent and convective features of turbulence producing structures. Several signal processing techniques were shown to extract detailed structural features of the turbulent motions. These techniques included digital band-pass filtering to discriminate between turbulent scales and a localized variance method for the detection of clusters of high frequency turbulent activity. Cross-spectral, cross-correlation, and conditional sampling methods applied to these data clearly show the dynamical relationships between coherent turbulent motions as well as their induced wall pressure signatures. Both pressure-velocity correlation results and conditionally averaged maps of the flow field sampled on peak wall pressure events, reveal a consistent correlation between large scale motions and near-wall, small scale turbulent production activity. The large scale vortical motions (or shear layers) extend across the turbulent boundary layer and exhibit Reynolds stress (turbulent production) characteristics. These findings are consistent with many of the proposed conceptual models of organized motions.
Author : M. V. Lowson
Publisher :
ISBN 13 :
Total Pages : 36 pages
Book Rating : 4.:/5 (31 download)
Download or read book Pressure Fluctuations in Turbulent Boundary Layers written by M. V. Lowson and published by . This book was released on 1965 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 892 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 1994 with total page 892 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Chao Zhang
Publisher :
ISBN 13 :
Total Pages : 149 pages
Book Rating : 4.:/5 (18 download)
Download or read book Direct Numerical Simulation of Pressure Fluctuations Induced by Supersonic Turbulent Boundary Layers written by Chao Zhang and published by . This book was released on 2018 with total page 149 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Direct Numerical Simulations are used to generate a database of high-speed zero-pressure-gradient turbulent boundary layers developing spatially over a flat plate with nominal freestream Mach number ranging from 2:5 to 14 and wall-to-recovery temperature ranging from 0:18 to 1:0. The flow conditions of the DNS are representative of the operational conditions of the Purdue Mach 6 quiet tunnel, the Sandia Hypersonic Wind Tunnel at Mach 8, and the AEDC Hypervelocity Tunnel No. 9 at Mach 14. The DNS database is used to gauge the performance of compressibility transformations, including the classical Morkovin's scaling and strong Reynolds analogy as well as the newly proposed mean velocity and temperature scalings that explicitly account for wall heat flux, examine the pressure fluctuations generated by the turbulent boundary layers. The unsteady pressure field is analyzed at multiple wall-normal locations, including those at the wall, within the boundary layer (including inner layer, the log layer, and the outer), and in the free stream. The statistical and structural variations of pressure fluctuations as a function of wall-normal distance are highlighted. The simulations show that the dominant frequency of boundary-layer-induced pressure fluctuations shifts to lower frequencies as the location of interest moves away from the wall. The pressure structures within the boundary layer and in the free stream evolve less rapidly as the wall temperature decreases, resulting in an increase in the decorrelation length of coherent pressure structures for the colder wall case. The pressure structures propagate with similar speeds for both wall temperatures. Acoustic sources are largely concentrated in the near-wall region; wall cooling most significantly influences the nonlinear (slow) component of the acoustic source term by enhancing dilatational fluctuations in the viscous sublayer while damping vortical fluctuations in the buffer and log layers. Precomputed flow statistics, including Reynolds stresses and their budgets, are available at the website of the NASA Langley Turbulence Modeling Resource"--Abstract, page iv.
Author : Mark E. Kammeyer
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (362 download)
Download or read book An Experimental Investigation of Organized Turbulent Motions and Wall-pressure Fluctuations in Complex Flows written by Mark E. Kammeyer and published by . This book was released on 1995 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Nan Hu
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (15 download)
Download or read book Investigation of Wall Pressure Fluctuations Induced by Turbulent Boundary Layer Flow with Pressure Gradients written by Nan Hu and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Andrew S. W. Thomas
Publisher :
ISBN 13 :
Total Pages : 512 pages
Book Rating : 4.F/5 ( download)
Download or read book Organized Structures in the Turbulent Boundary Layer written by Andrew S. W. Thomas and published by . This book was released on 1977 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Ramis Örlü
Publisher : Springer Nature
ISBN 13 : 3030221962
Total Pages : 339 pages
Book Rating : 4.0/5 (32 download)
Download or read book Progress in Turbulence VIII written by Ramis Örlü and published by Springer Nature. This book was released on 2019-08-27 with total page 339 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume collects the edited and reviewed contributions presented in the 8th iTi Conference on Turbulence, held in Bertinoro, Italy, in September 2018. In keeping with the spirit of the conference, the book was produced afterwards, so that the authors had the opportunity to incorporate comments and discussions raised during the event. The respective contributions, which address both fundamental and applied aspects of turbulence, have been structured according to the following main topics: I TheoryII Wall-bounded flowsIII Simulations and modellingIV ExperimentsV Miscellaneous topicsVI Wind energy/div
Author :
Publisher :
ISBN 13 :
Total Pages : 52 pages
Book Rating : 4.:/5 (317 download)
Download or read book On the Structure of Wall-bounded Turbulent Flows written by and published by . This book was released on 1983 with total page 52 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : A. A. R. Townsend
Publisher : Cambridge University Press
ISBN 13 : 9780521298193
Total Pages : 450 pages
Book Rating : 4.2/5 (981 download)
Download or read book The Structure of Turbulent Shear Flow written by A. A. R. Townsend and published by Cambridge University Press. This book was released on 1976 with total page 450 pages. Available in PDF, EPUB and Kindle. Book excerpt: Develops a physical theory from the mass of experimental results, with revisions to reflect advances of recent years.
Author : Herman Branover
Publisher : Academic Press
ISBN 13 : 9780121257408
Total Pages : 296 pages
Book Rating : 4.2/5 (574 download)
Download or read book Turbulence and Structures written by Herman Branover and published by Academic Press. This book was released on 1999 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence is one of the most wide-spread phenomena in the universe. It relates to processes within the atmosphere, ocean, deep within the earth, as well as to the stars. The general public usually knows about turbulence from the unpleasant shaking of an airplane, or from disastrous atmospheric phenomena such as typhoons and hurricanes. The chaotic and unpredictable behavior of turbulent movement makes it very difficult to study. The degree of understanding of turbulence is still far from being complete. Some progress was made with the recent advent of a new science--chaos theory. The authors succeeded in examining one basic feature of turbulence called helicity (or spirality) which is the foundation of explaining and predicting the generation of large turbulent structures (e.g. typhoons). Helicity is a universal feature existing not only in fluid flows but also in solid bodies and even in living organisms. This book can be especially useful for researchers and students in fluid mechanics, plasma, geophysics, biology, and meteorology. * Examines the helical mechanism of self-organization in nature and laboratory * Presents a unified approach to chaos and theory * Discusses similarities and differences in the formation of dynamic and magnetic structures * Successfully combines profound theoretical and experimental knowledge * Includes a disk with an expanded bibliographical database
Author : G. M. Lilley
Publisher :
ISBN 13 :
Total Pages : 6 pages
Book Rating : 4.:/5 (11 download)
Download or read book On Wall Pressure Fluctuations in Turbulent Boundary Layers written by G. M. Lilley and published by . This book was released on 1962 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 532 pages
Book Rating : 4.0/5 ( download)
Download or read book 29th AIAA Fluid Dynamics Conference written by and published by . This book was released on 1998 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
