Numerical Simulation of Supersonic Jet Noise Phenomena PDF Download
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Author: L. N. Sankar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: L. N. Sankar
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: R. Hixon
Publisher:
ISBN:
Category : Computational aeroacoustics
Languages : en
Pages : 24
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Author: National Aeronautics and Space Adm Nasa
Publisher: Independently Published
ISBN: 9781792791574
Category :
Languages : en
Pages : 34
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Book Description
Progress associated with research in (1) physics and prediction of turbulent mixing noise from supersonic jets, and (2) numerical simulation of supersonic jet noise is reported. Tam, Christopher Langley Research Center NASA-CR-203579, NAS 1.26:203579 NAG1-1776...
Author: Ibraheem M. A. Al-Qadi
Publisher:
ISBN:
Category : Aerodynamic noise
Languages : en
Pages :
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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: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781722117566
Category :
Languages : en
Pages : 36
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The research project has been a computational study of computational aeroacoustics algorithms and numerical simulations of the flow and noise of supersonic jets. During this study a new method for the implementation of solid wall boundary conditions for complex geometries in three dimensions has been developed. In addition, a detailed study of the simulation of the flow in and noise from supersonic circular and rectangular jets has been conducted. Extensive comparisons have been made with experimental measurements. A summary of the results of the research program are attached as the main body of this report in the form of two publications. Also, the report lists the names of the students who were supported by this grant, their degrees, and the titles of their dissertations. In addition, a list of presentations and publications made by the Principal Investigators and the research students is also included. Morris, Philip J. and Long, Lyle N. Langley Research Center NAG1-1479...
Author: Lockheed-Georgia Company
Publisher:
ISBN:
Category : Jet planes
Languages : en
Pages : 270
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Twin jets emanating from closely spaced nozzles can interact quite unpredictably and give rise to high dynamic pressures in the internozzle region which can result in sonic fatigue of sensitive aircraft equipment. This project studies the interaction between two such jet from nozzles having a single beveled exit geometry. Such nozzles are finding increasing use in modern aircraft due to the thrust vectoring and performance advantages they present. The study begins by using traditional linear spectral analysis techniques to study the coupling mechanism. It goes on to reveal the limitations of such linear techniques for understanding phenomena that are as complex as the one studied in this project and uses non-linear techniques to uncover results that have hitherto gone unreported. It is hoped that the results of these techniques will be of use to nozzle designers as well as to scientists involved in the field of numerical simulation of jet noise so as to provide benchmark data for the validation of their models.
Author: Ram Mohan Rao
Publisher:
ISBN:
Category :
Languages : en
Pages : 264
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Author: K. Viswanathan
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Author: Christophe Brun
Publisher: Springer Science & Business Media
ISBN: 3540899561
Category : Technology & Engineering
Languages : en
Pages : 344
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Book Description
Large Eddy Simulation (LES) is a high-fidelity approach to the numerical simulation of turbulent flows. Recent developments have shown LES to be able to predict aerodynamic noise generation and propagation as well as the turbulent flow, by means of either a hybrid or a direct approach. This book is based on the results of two French/German research groups working on LES simulations in complex geometries and noise generation in turbulent flows. The results provide insights into modern prediction approaches for turbulent flows and noise generation mechanisms as well as their use for novel noise reduction concepts.
