Effect Of Swirl On Turbulent Structures In Supersonic Jets PDF Download
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Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 36 |
Release | : 2018-07-02 |
Genre | : |
ISBN | : 9781722192457 |
Download Effect of Swirl on Turbulent Structures in Supersonic Jets Book in PDF, ePub and Kindle
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...
Author | : National Aeronautics and Space Administration (NASA) |
Publisher | : Createspace Independent Publishing Platform |
Total Pages | : 34 |
Release | : 2018-07-05 |
Genre | : |
ISBN | : 9781722333546 |
Download Large Scale Turbulent Structures in Supersonic Jets Book in PDF, ePub and Kindle
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..
Author | : Erina Murakami |
Publisher | : |
Total Pages | : 144 |
Release | : 1998 |
Genre | : Airplanes |
ISBN | : |
Download Evolution of Large-scale Turbulent Structures in Coannular Supersonic Jets Book in PDF, ePub and Kindle
Author | : Alexander J. Smits |
Publisher | : Springer Science & Business Media |
Total Pages | : 418 |
Release | : 2006-05-11 |
Genre | : Science |
ISBN | : 0387263055 |
Download Turbulent Shear Layers in Supersonic Flow Book in PDF, ePub and Kindle
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 | : Jason E. Frank |
Publisher | : |
Total Pages | : |
Release | : 1994 |
Genre | : |
ISBN | : |
Download Experimental Investigation of the Effect of Swirl on Mixing Enhancement of Supersonic Rectangular Jets Book in PDF, ePub and Kindle
Author | : Harry Edward Bailey |
Publisher | : |
Total Pages | : 54 |
Release | : 1958 |
Genre | : Aerodynamics, Supersonic |
ISBN | : |
Download Supersonic Mixing of Jets and Turbulent Boundary Layers Book in PDF, ePub and Kindle
Author | : United States. Superintendent of Documents |
Publisher | : |
Total Pages | : 1072 |
Release | : 1993 |
Genre | : Government publications |
ISBN | : |
Download Monthly Catalog of United States Government Publications Book in PDF, ePub and Kindle
February issue includes Appendix entitled Directory of United States Government periodicals and subscription publications; September issue includes List of depository libraries; June and December issues include semiannual index
Author | : Ram Mohan Rao |
Publisher | : |
Total Pages | : 264 |
Release | : 1997 |
Genre | : |
ISBN | : |
Download Direct Numerical Simulation of Turbulent Supersonic Jets Book in PDF, ePub and Kindle
Author | : |
Publisher | : |
Total Pages | : 702 |
Release | : 1995 |
Genre | : Aeronautics |
ISBN | : |
Download Scientific and Technical Aerospace Reports Book in PDF, ePub and Kindle
Author | : Jianjun Zhang |
Publisher | : |
Total Pages | : 256 |
Release | : 1992 |
Genre | : Aerodynamics |
ISBN | : |
Download Investigation of Turbulent Structures in a Supersonic Free Shear Layer Book in PDF, ePub and Kindle