Numerical Simulations of the Structure of Supersonic Shear Layers PDF Download
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Author: B. Farouk
Publisher:
ISBN:
Category :
Languages : en
Pages : 42
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Book Description
Time-dependent two-dimensional numerical calculations were performed to study the mixing characteristics of unforced, planar, confined shear layers formed by two parallel streams of air that come into contact after passing over a splitter plate. The evolution of the shear layer was examined by systematically varying the velocities, densities, and the static pressures of the two streams that come into contact at the trailing edge of the plate. At least one of the streams was always supersonic. For the range of the parameters studied, the supersonic shear layers show some organization, albeit less coherent than their subsonic counterparts. The most amplified frequency, obtained by Fourier analysis of the velocity and pressure fluctuations, depends on the effective inlet momentum thickness. Convective Mach numbers of the streams corresponding to each side of the shear layer were found to be quite different. The simulations indicate that the single convective Mach number as derived from an isentropic model is not sufficient to characterize the mixing behavior when the velocity, pressure, and density ratios are changed independently. Keywords: Numerical simulations; Supersonic shear layers. (jhd).
Author: B. Farouk
Publisher:
ISBN:
Category :
Languages : en
Pages : 42
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Book Description
Time-dependent two-dimensional numerical calculations were performed to study the mixing characteristics of unforced, planar, confined shear layers formed by two parallel streams of air that come into contact after passing over a splitter plate. The evolution of the shear layer was examined by systematically varying the velocities, densities, and the static pressures of the two streams that come into contact at the trailing edge of the plate. At least one of the streams was always supersonic. For the range of the parameters studied, the supersonic shear layers show some organization, albeit less coherent than their subsonic counterparts. The most amplified frequency, obtained by Fourier analysis of the velocity and pressure fluctuations, depends on the effective inlet momentum thickness. Convective Mach numbers of the streams corresponding to each side of the shear layer were found to be quite different. The simulations indicate that the single convective Mach number as derived from an isentropic model is not sufficient to characterize the mixing behavior when the velocity, pressure, and density ratios are changed independently. Keywords: Numerical simulations; Supersonic shear layers. (jhd).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Time-dependent two-dimensional numerical calculations were performed to study the mixing characteristics of unforced, planar, confined shear layers formed by two parallel streams of air that come into contact after passing over a splitter plate. The evolution of the shear layer was examined by systematically varying the velocities, densities, and the static pressures of the two streams that come into contact at the trailing edge of the plate. At least one of the streams was always supersonic. For the range of the parameters studied, the supersonic shear layers show some organization, albeit less coherent than their subsonic counterparts. The most amplified frequency, obtained by Fourier analysis of the velocity and pressure fluctuations, depends on the effective inlet momentum thickness. Convective Mach numbers of the streams corresponding to each side of the shear layer were found to be quite different. The simulations indicate that the single convective Mach number as derived from an isentropic model is not sufficient to characterize the mixing behavior when the velocity, pressure, and density ratios are changed independently. Keywords: Numerical simulations; Supersonic shear layers. (jhd).
Author: Alexander J. Smits
Publisher: Springer Science & Business Media
ISBN: 0387263055
Category : Science
Languages : en
Pages : 418
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Book Description
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:
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Category :
Languages : en
Pages : 0
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Book Description
The investigation of the shock-wave structure and numerical characteristics of supersonic-jet shear layer is of great importance due to numerous applications of supersonic jets in aerospace engineering. In the present work, a detailed study of a supersonic non-isobaric jet aimed at validation and further development of numerical algorithms for jet flow prediction has been carried out. The difficulties in numerical simulation of supersonic non-isobaric jets stem from the necessity of accurate resolution of various flow scales and from the occurrence of multiple shock waves and subsonic pockets interacting with each other.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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The objective of the current research is to study the mixing and stability characteristics of three dimensional supersonic free shear flows through a direct numerical solution of 3-D compressible flow equations. Supersonic shear flows are of interest to SCRAMJET engine designers. The successful operation of these engines requires rapid and efficient (i.e. minimum total pressure loss) mixing of supersonic airstreams and subsonic/sonic fuel streams. (jhd).
Author: L. J. Sankar
Publisher:
ISBN:
Category :
Languages : en
Pages : 15
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Book Description
The objective of the current research is to study the mixing and stability characteristics of three dimensional supersonic free shear flows through a direct numerical solution of 3-D compressible flow equations. Supersonic shear flows are of interest to SCRAMJET engine designers. The successful operation of these engines requires rapid and efficient (i.e. minimum total pressure loss) mixing of supersonic airstreams and subsonic/sonic fuel streams. (jhd).
Author: John Philip Drummond
Publisher:
ISBN:
Category : Fluid mechanics
Languages : en
Pages : 112
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Author: Rohan J. Banton
Publisher:
ISBN:
Category :
Languages : en
Pages : 274
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Author: Ibraheem M. A. Al-Qadi
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages :
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Book Description
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.
Author: Alexander J. Smits
Publisher:
ISBN:
Category : Reynolds number
Languages : en
Pages : 50
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Book Description
