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Large Scale Turbulent Structures In Supersonic Jets
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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..
Book Synopsis Evolution of Large-scale Turbulent Structures in Coannular Supersonic Jets by : Erina Murakami
Download or read book Evolution of Large-scale Turbulent Structures in Coannular Supersonic Jets written by Erina Murakami and published by . This book was released on 1998 with total page 144 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Coherent Large-scale Structures in High Reynolds Number Supersonic Jets by : J. Lepicovsky
Download or read book Coherent Large-scale Structures in High Reynolds Number Supersonic Jets written by J. Lepicovsky and published by . This book was released on 1985 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The flow structure of a 50.8 mm (2 in) diameter jet operated at a full expanded Mach number of 1.37, with Reynolds numbers in the range 1.7 to 2.35 million, was examined for the first 20 jet diameters. To facilitate the study of the large scale structure, and determine any coherence, a discrete tone acoustic excitation method was used. Phase locked flow visualization as well as laser velocimeter quantitative measurements were made. The main conclusions derived from this study are: (1) large scale coherent like turbulence structures do exist in large Reynolds number supersonic jets, and they prevail even beyond the potential core; (2) the most preferential Strouhal number for these structures is in the vicinity of 0.4; and (3) quantitatively, the peak amplitudes of these structures are rather low, and are about 1% of the jet exit velocity. Finally, since a number of unique problems related to LV measurements in supersonic jets were encountered, a summary of these problems and lessons learned therefrom are also reported.
Book Synopsis Coherent Large-scale Structures in High Reynolds Number Supersonic Jets by :
Download or read book Coherent Large-scale Structures in High Reynolds Number Supersonic Jets written by and published by . This book was released on 1985 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Role of Large Scale Structures in the Noise Generation of a Turbulent Supersonic Jet by : Birendra Dutt
Download or read book Role of Large Scale Structures in the Noise Generation of a Turbulent Supersonic Jet written by Birendra Dutt and published by . This book was released on 1977 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781722192457 Total Pages :36 pages Book Rating :4.1/5 (924 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 36 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 Moserl 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 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:
Book Synopsis Dynamics of Supersonic Jet in Crossflow and Liquid Plug Rupture by : Hassan Ez
Download or read book Dynamics of Supersonic Jet in Crossflow and Liquid Plug Rupture written by Hassan Ez and published by LAP Lambert Academic Publishing. This book was released on 2014-02 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multi-fluid dynamics' simulations require numerical treatments based on the flow characteristics, including flow speed, turbulence, thermodynamic state, and time/length scales. Two distinct problems are investigated: supersonic jet and crossflow interactions; and liquid plug propagation and rupture in lung airways. Supersonic crossflow is the mechanism for fuel injection in SCRAMJET engines. The regime is highly unsteady, involving shocks, turbulent mixing, and large-scale vortical structures. An eddy-viscosity-based multi-scale turbulence model is proposed to resolve turbulent structures consistent with grid resolution and turbulence length scales. Additionally, an adaptive turbulent mixing approach is also proposed. Predictions from the new models show great improvement over the standard RANS models. For liquid plug rupture, simulations are conducted using an Eulerian-Lagrangian approach with a continuous-interface method. A new reconstruction scheme is developed to capture plug rupture by altering the connectivity information of the interface mesh.During the plug rupture process, a sudden increase of mechanical stresses on the tube wall is recorded, which can cause tissue damage
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 High Resolution Measurements of Supersonic Mixing and Combustion in Coflowing Turbulent Jets by :
Download or read book High Resolution Measurements of Supersonic Mixing and Combustion in Coflowing Turbulent Jets written by and published by . This book was released on 1998 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: An experimental study of compressibility effects on the large scale structure and outer variable scaling laws of a coflowing turbulent jet was partially completed. Results showed distinct large scale structure and classical incompressible scaling where the convective Mach number has decreased to subsonic values. At supersonic convective Mach numbers no large scale structure was seen and incompressible scalings were dramatically modified. Experiments also showed strong effects due to oblique shock wave interactions with combustion in supersonic turbulent jets. OH PLIF imaging measurements comparing subsonic and supersonic jets documented striking differences in their mixing and combustion properties. Combined OH/CH PLIF imaging measurements found large differences in the combustion properties of jet flames created by small differences in the fuel injection design. A theoretical study of density effects due to combustion heat release on the outer variable scalings of turbulent shear flows was completed. This study produced a general methodology for predicting the changes in such quantities as growth rates, velocity decay, and entrainment and mixing rates due to heat release. Comparisons with measured heat release effects in the literature, including planar and axisymmetric jet flames as well as mixing layers, showed excellent agreement with this general approach.
Book Synopsis Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air by : Khaled Sayed Abdol-Hamid
Download or read book Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air written by Khaled Sayed Abdol-Hamid and published by . This book was released on 1987 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis The Generation and Radiation of Supersonic Jet Noise: Theory of turbulence generated jet noise, noise radiation from upstream sources, and combustion noise by :
Download or read book The Generation and Radiation of Supersonic Jet Noise: Theory of turbulence generated jet noise, noise radiation from upstream sources, and combustion noise written by and published by . This book was released on 1972 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air by : Khaled S. Abdol-Hamid
Download or read book Multiscale Turbulence Effects in Supersonic Jets Exhausting Into Still Air written by Khaled S. Abdol-Hamid and published by . This book was released on 1987 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Investigation of Supersonic Boundary Layer Transition and Turbulent Structure by : Alexander J. Smits
Download or read book Investigation of Supersonic Boundary Layer Transition and Turbulent Structure written by Alexander J. Smits and published by . This book was released on 1990 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 The Theory of Turbulent Jets by : Genrikh Naumovich Abramovich
Download or read book The Theory of Turbulent Jets written by Genrikh Naumovich Abramovich and published by Mit Press. This book was released on 1963 with total page 671 pages. Available in PDF, EPUB and Kindle. Book excerpt: The author's first monograph on turbulent jets, in 1936, dealt solely with a free submerged jet. Since that time, the theory of the turbulent jet has been developed in many published works both in the USSR and abroad: it has been enriched with a large amount of experimental material and has been applied in many new fields of engineering. In the last 10 years very substantial progress has been made, and it has now become possible to go beyond the free submerged jet and to solve the problem of a jet in a stream of fluid, to take into account the interaction between the jet and solid walls, to ascertain the relationship between the contour of the jet and the ratio of its density to the density of the surrounding medium, and to establish the characteristic features of a supersonic jet. This monograph contains the results of further research by the author and his colleagues, as well as a critical reappraisal of the more important theoretical and experimental data published by other investigators. The first section deals with the theory of a turbulent jet of incompressible fluid. It gives a systematic analysis of numerous experimental data on velocity profiles, temperature, and the impurity concentration, as well as the outlines of the turbulent mixing lone. The second section sets forth the theory of turbulent gas jets, including strongly preheated and supersonic jets. The theory of free turbulence in a gas, suitable in principle for any degree of compressibility, is revised, and the equations are derived for motion and heat exchange in the boundary layer of a jet at very high temperature. The third section solves several problems of the spreading of jets in finite and semifinite space, and the fourth section describes various applications of the theory of jets, many of which are reported for the first time or have been significantly revised.
Book Synopsis Aeroacoustics of Flight Vehicles by : Harvey H. Hubbard
Download or read book Aeroacoustics of Flight Vehicles written by Harvey H. Hubbard and published by . This book was released on 1991 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
