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Direct Numerical Simulation Of Turbulent Supersonic Jets
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Book Synopsis Direct Numerical Simulation of Turbulent Supersonic Jets by : Ram Mohan Rao
Download or read book Direct Numerical Simulation of Turbulent Supersonic Jets written by Ram Mohan Rao and published by . This book was released on 1997 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722192693 Total Pages :30 pages Book Rating :4.1/5 (926 download)
Book Synopsis Effect of Swirl on Turbulent Structures in Supersonic Jets by : National Aeronautics and Space Administration (NASA)
Download or read book Effect of Swirl on Turbulent Structures in Supersonic Jets written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-02 with total page 30 pages. Available in PDF, EPUB and Kindle. Book excerpt: Direct numerical simulation (DNS) is used to study the mechanism of generation and evolution of turbulence structures in a temporally evolving supersonic swirling round jet and also to examine the resulting acoustic radiations. Fourier spectral expansions are used in the streamwise and azimuthal directions and a 1-D b-spline Galerkin representation is used in the radial direction. Spectral-like accuracy is achieved using this numerical scheme. Direct numerical simulations, using the b-spline spectral method, are carried out starting from mean flow initial conditions which are perturbed by the most unstable linear stability eigenfunctions. It is observed that the initial.helical instability waves evolve into helical vortices which eventually breakdown into smaller scales of turbulence. 'Rib' structures similar to those seen in incompressible mixing layer flow of Rogers and Moser are observed. The jet core breakdown stage exhibits increased acoustic radiations. Rao, Ram Mohan and Lundgren, Thomas S. Ames Research Center NCC2-5221...
Book Synopsis Direct Numerical Simulation of Supersonic Turbulent Boundary Layers by : Stephen Guarini
Download or read book Direct Numerical Simulation of Supersonic Turbulent Boundary Layers written by Stephen Guarini and published by . This book was released on 1998 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Turbulent Shear Layers in Supersonic Flow by : Alexander J. Smits
Download or read book Turbulent Shear Layers in Supersonic Flow written by Alexander J. Smits and published by Springer Science & Business Media. This book was released on 2006-05-11 with total page 418 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Book Synopsis Acoustic Control of Turbulent Jets by : A.S. Ginevsky
Download or read book Acoustic Control of Turbulent Jets written by A.S. Ginevsky and published by Springer Science & Business Media. This book was released on 2004-01-22 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph presents recent results of experimental research relating to control of aerodynamic and acoustic characteristics of subsonic and supersonic turbulent jets by acoustic excitation of different intensity and frequency. Coherent structures in subsonic turbulent jets and their sensibility to harmonic acoustic excitation are studied, as well as the generation and suppression of turbulence in subsonic jets under acoustic excitation. The book covers active and passive methods of controlling supersonic non-isobaric jet characteristics and, in particular, suppression of discrete components of aerodynamic jet noise. Numerical simulation methods of subsonic turbulent jets are analyzed. Examples of practical realization of the presented methods are given in application to jet noise reduction of turbojet engines and to auto-oscillation suppression in wind tunnels with open test section.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721518654 Total Pages :38 pages Book Rating :4.5/5 (186 download)
Book Synopsis Numerical Simulation of a Spatially Evolving Supersonic Turbulent Boundary Layer by : National Aeronautics and Space Administration (NASA)
Download or read book Numerical Simulation of a Spatially Evolving Supersonic Turbulent Boundary Layer written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 38 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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
Book Synopsis Modeling and Simulation of Turbulent Mixing and Reaction by : Daniel Livescu
Download or read book Modeling and Simulation of Turbulent Mixing and Reaction written by Daniel Livescu and published by Springer Nature. This book was released on 2020-02-19 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book highlights recent research advances in the area of turbulent flows from both industry and academia for applications in the area of Aerospace and Mechanical engineering. Contributions include modeling, simulations and experiments meant for researchers, professionals and students in the area.
Book Synopsis Numerical Simulation of a Spatially Evolving Supersonic Turbulent Boundary Layer by :
Download or read book Numerical Simulation of a Spatially Evolving Supersonic Turbulent Boundary Layer written by and published by . This book was released on 2002 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721298853 Total Pages :34 pages Book Rating :4.2/5 (988 download)
Book Synopsis An Evaluation of Linear Instability Waves As Sources of Sound in a Supersonic Turbulent Jet by : National Aeronautics and Space Administration (NASA)
Download or read book An Evaluation of Linear Instability Waves As Sources of Sound in a Supersonic Turbulent Jet written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-20 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mach wave radiation from supersonic jets is revisited to better quantify the extent to which linearized equations represent the details of the actual mechanism. To this end, we solve the linearized Navier-Stokes equations (LNS) with precisely the same mean flow and inflow disturbances as a previous direct numerical simulation (DNS) of a perfectly expanded turbulent M = 1.92 jet. We restrict our attention to the first two azimuthal modes, n = 0 and n = 1, which constitute most of the acoustic field. The direction of peak radiation and the peak Strouhal number matches the DNS reasonably well, which is in accord with previous experimental justification of the linear theory. However, it is found that the sound pressure level predicted by LNS is significantly lower than that from DNS. In order to investigate the discrepancy, individual frequency components of the solution are examined. These confirm that near the peak Strouhal number, particularly for the first helical mode n = 1, the amplification of disturbances in the LNS closely matches the DNS. However, away from the peak frequency (and generally for the azimuthal mode n = 0), modes in the LNS are damped while those in the DNS grow at rates comparable to those at the peak Strouhal number. Mohseni, Kamran and Colonius, Tim and Freund, Jonathan B. Glenn Research Center
Book Synopsis On the Coupling Between a Supersonic Turbulent Boundary Layer and a Flexible Structure by : Abdelkader Frendi
Download or read book On the Coupling Between a Supersonic Turbulent Boundary Layer and a Flexible Structure written by Abdelkader Frendi and published by . This book was released on 1996 with total page 46 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Direct Numerical Simulation for Turbulent Reacting Flows by : Thierry Baritaud
Download or read book Direct Numerical Simulation for Turbulent Reacting Flows written by Thierry Baritaud and published by Editions TECHNIP. This book was released on 1996 with total page 328 pages. Available in PDF, EPUB and Kindle. Book excerpt: Contents: Description of accurate boundary conditions for the simulation of reactive flows. Parallel direct numerical simulation of turbulent reactive flow. Flame-wall interaction and heat flux modelling in turbulent channel flow. A numerical study of laminar flame wall interaction with detailed chemistry: wall temperature effects. Modeling and simulation of turbulent flame kernel evolution. Experimental and theoretical analysis of flame surface density modelling for premixed turbulent combustion. Gradient and counter-gradient transport in turbulent premixed flames. Direct numerical simulation of turbulent flames with complex chemical kinetics. Effects of curvature and unsteadiness in diffusion flames. Implications for turbulent diffusion combustion. Numerical simulations of autoignition in turbulent mixing flows. Stabilization processes of diffusion flames. References.
Book Synopsis Three-dimensional Numerical Simulation of a Supersonic Under-expanded Rectangular Jet by : Ibraheem M. A. Al-Qadi
Download or read book Three-dimensional Numerical Simulation of a Supersonic Under-expanded Rectangular Jet written by Ibraheem M. A. Al-Qadi and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: A three-dimensional numerical simulation of the unsteady flow in an under-expanded supersonic rectangular jet has been conducted for the purpose of investigating and analyzing the production and propagation of jet noise. The compressible three-dimensional Navier-Stokes equations are solved using high-order spatial and temporal differencing schemes. The solution method applies linear and nonlinear filtering schemes to produce oscillation-free shocks and discontinuities while minimizing dissipation effects in smooth regions. The solution method also applies nonreflecting boundary conditions to minimize reflections. Characteristic boundary conditions are implemented at the upstream and far-field boundaries and an absorbing buffer zone is added at the outflow boundary. OpenMP shared- memory model was utilized to parallelize the simulation and good parallel performance was achieved. The code was used to conduct a time dependent numerical simulation of an under-expanded supersonic rectangular jet. A comprehensive database of the simulation was generated. The results of the simulation were validated against experimental measurements and show very good agreement. The simulation is shown to resolve critical unsteady flow features of the jet such as vortex shedding, shock-cell structure, shock shear-layer interaction, flapping, and axis-switching. Visualization of the unsteady flow and analysis of the turbulent flow-field shows that the location of axis-switching is immediately downstream of the fourth shock. It is also observed that the location of the dominant screech source is at the third shock. Two-point space-time correlations demonstrate that the convection velocities in the jet shear layer are highly modulated by the presence of shock waves. Spectral analysis show that the simulation predicts, with good accuracy, screech modes frequencies, wavelengths, phase, and amplitudes. Analysis inside the jet shear layer and in the acoustic near-field reveal exact correspondence in frequency and phase between the inner and the outer parts of the screech loop. The simulation also predicts the complex pattern of the near acoustic field associated with screech. The current simulation represents the first successful three- dimensional numerical simulation of an under-expanded supersonic rectangular jet. It also represents a significant contribution towards accurate prediction of noise production and far-field radiation in supersonic jets. The computational tools developed in this study can be used to investigate a wide range of problems related to unsteady flows and aeroacoustics.
Book Synopsis Studies in Turbulence by : Thomas B. Gatski
Download or read book Studies in Turbulence written by Thomas B. Gatski and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 609 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains contributions by former students, colleagues and friends of Professor John L. Lumley, on the occasion of his 60th birthday, in recognition of his enormous impact on the advancement of turbulence research. A variety of experimental, computational and theoretical topics, including turbulence modeling, direct numerical simulations, compressible turbulence, turbulent shear flows, coherent structures and the Proper Orthogonal Decomposition are contained herein. The diversity and scope of these contributions are further acknowledgment of John Lumley's wide ranging influence in the field of turbulence. The large number of contributions by the authors, many of whom were participants in The Lumley Symposium: Recent Developments in Turbulence (held at ICASE, NASA Langley Research Center on November 12 & 13, 1990), has presented us with the unique opportu nity to select a few numerical and theoretical papers for inclusion in the journal Theoretical and Computational Fluid Dynamics for which Professor Lumley serves as Editor. Extended Abstracts of these pa pers are included in this volume and are appropriately marked. The special issue of TCFD will appear this year and will serve as an additional tribute to John Lumley. As is usually the case, the efforts of others have significantly eased our tasks. We would like to express our deep appreciation to Drs. R.
Book Synopsis Analysis of Turbulence Statistics in Three-dimensional, Air-to-air Supersonic Shear Layers Using Direct Numerical Simulation by : Daniel J. Risha
Download or read book Analysis of Turbulence Statistics in Three-dimensional, Air-to-air Supersonic Shear Layers Using Direct Numerical Simulation written by Daniel J. Risha and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Transition and Turbulence Control by : Mohamed Gad-el-Hak
Download or read book Transition and Turbulence Control written by Mohamed Gad-el-Hak and published by World Scientific. This book was released on 2006 with total page 445 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume contains articles based on lectures given at the Workshop on Transition and Turbulence Control, hosted by the Institute for Mathematical Sciences, National University of Singapore, 8OCo10 December 2004. The lecturers included 13 of the worldOCOs foremost experts in the control of transitioning and turbulent flows. The chapters cover a wide range of subjects in the broad area of flow control, and will be useful to researchers working in this area in academia, government laboratories and industry. The coverage includes control theory, passive, active and reactive methods for controlling transitional and turbulent wall-bounded flows, noise suppression and mixing enhancement of supersonic turbulent jets, compliant coatings, modern flow diagnostic systems, and swept wing instabilities."
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722333546 Total Pages :34 pages Book Rating :4.3/5 (335 download)
Book Synopsis Large Scale Turbulent Structures in Supersonic Jets by : National Aeronautics and Space Administration (NASA)
Download or read book Large Scale Turbulent Structures in Supersonic Jets written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-07-05 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: Jet noise is a major concern in the design of commercial aircraft. Studies by various researchers suggest that aerodynamic noise is a major contributor to jet noise. Some of these studies indicate that most of the aerodynamic jet noise due to turbulent mixing occurs when there is a rapid variation in turbulent structure, i.e. rapidly growing or decaying vortices. The objective of this research was to simulate a compressible round jet to study the non-linear evolution of vortices and the resulting acoustic radiations. In particular, to understand the effect of turbulence structure on the noise. An ideal technique to study this problem is Direct Numerical Simulations (DNS), because it provides precise control on the initial and boundary conditions that lead to the turbulent structures studied. It also provides complete 3-dimensional time dependent data. Since the dynamics of a temporally evolving jet are not greatly different from those of a spatially evolving jet, a temporal jet problem was solved, using periodicity in the direction of the jet axis. This enables the application of Fourier spectral methods in the streamwise direction. Physically this means that turbulent structures in the jet are repeated in successive downstream cells instead of being gradually modified downstream into a jet plume. The DNS jet simulation helps us understand the various turbulent scales and mechanisms of turbulence generation in the evolution of a compressible round jet. These accurate flow solutions will be used in future research to estimate near-field acoustic radiation by computing the total outward flux across a surface and determine how it is related to the evolution of the turbulent solutions. Furthermore, these simulations allow us to investigate the sensitivity of acoustic radiations to inlet/boundary conditions, with possible appli(, a- tion to active noise suppression. In addition, the data generated can be used to compute, various turbulence quantities such as mean velociti..