Direct Numerical Simulation Of Pressure Fluctuations Induced By Supersonic Turbulent Boundary Layers
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Author | : Chao Zhang |
Publisher | : |
Total Pages | : 149 |
Release | : 2018 |
Genre | : |
ISBN | : |
"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 | : Stephen Guarini |
Publisher | : |
Total Pages | : 161 |
Release | : 1998 |
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Author | : Abdelkader Frendi |
Publisher | : |
Total Pages | : 46 |
Release | : 1996 |
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Author | : |
Publisher | : |
Total Pages | : 26 |
Release | : 2002 |
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Author | : Alexander J. Smits |
Publisher | : Springer Science & Business Media |
Total Pages | : 418 |
Release | : 2006-05-11 |
Genre | : Science |
ISBN | : 0387263055 |
A good understanding of turbulent compressible flows is essential to the design and operation of high-speed vehicles. Such flows occur, for example, in the external flow over the surfaces of supersonic aircraft, and in the internal flow through the engines. Our ability to predict the aerodynamic lift, drag, propulsion and maneuverability of high-speed vehicles is crucially dependent on our knowledge of turbulent shear layers, and our understanding of their behavior in the presence of shock waves and regions of changing pressure. Turbulent Shear Layers in Supersonic Flow provides a comprehensive introduction to the field, and helps provide a basis for future work in this area. Wherever possible we use the available experimental work, and the results from numerical simulations to illustrate and develop a physical understanding of turbulent compressible flows.
Author | : Ferhat F. Hatay |
Publisher | : |
Total Pages | : |
Release | : 1995 |
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ISBN | : |
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 38 |
Release | : 2018-06-20 |
Genre | : |
ISBN | : 9781721518654 |
The results from direct numerical simulations of a spatially evolving, supersonic, flat-plate turbulent boundary-layer flow, with free-stream Mach number of 2.25 are presented. The simulated flow field extends from a transition region, initiated by wall suction and blowing near the inflow boundary, into the fully turbulent regime. Distributions of mean and turbulent flow quantities are obtained and an analysis of these quantities is performed at a downstream station corresponding to Re(sub x)= 5.548 x10(exp 6) based on distance from the leading edge. Gatski, T. B. and Erlebacher, G. Langley Research Center NASA/TM-2002-211934, NAS 1.15:211934, L-18225
Author | : |
Publisher | : |
Total Pages | : 40 |
Release | : 1997 |
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ISBN | : |
Author | : E. T. Fick |
Publisher | : |
Total Pages | : |
Release | : 1996 |
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ISBN | : |
Author | : Holger Babinsky |
Publisher | : Cambridge University Press |
Total Pages | : 481 |
Release | : 2011-09-12 |
Genre | : Technology & Engineering |
ISBN | : 1139498649 |
Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.