The Aeroacoustics Of Supersonic Coaxial Jets
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The Aeroacoustics Of Supersonic Coaxial Jets
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-07-23
The Aeroacoustics Of Supersonic Coaxial Jets written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-07-23 with categories.
Instability waves have been established as the dominant source of mixing noise radiating into the downstream arc of a supersonic jet when the waves have phase velocities that are supersonic relative to ambient conditions. Recent theories for supersonic jet noise have used the concepts of growing and decaying linear instability waves for predicting radiated noise. This analysis is extended to the prediction of noise radiation from supersonic coaxial jets. Since the analysis requires a known mean flow and the coaxial jet mean flow is not described easily in terms of analytic functions, a numerical prediction is made for its development. The Reynolds averaged, compressible, boundary layer equations are solved using a mixing length turbulence model. Empirical correlations are developed for the effects of velocity and temperature ratios and Mach number. Both normal and inverted velocity profile coaxial jets are considered. Comparisons with measurements for both single and coaxial jets show good agreement. The results from mean flow and stability calculations are used to predict the noise radiation from coaxial jets with different operating conditions. Comparisons are made between different coaxial jets and a single equivalent jet with the same total thrust, mass flow, and exit area. Results indicate that normal velocity profile jets can have noise reductions compared to the single equivalent jet. No noise reductions are found for inverted velocity profile jets operated at the minimum noise condition compared to the single equivalent jet. However, it is inferred that changes in area ratio may provide noise reduction benefits for inverted velocity profile jets. Dahl, Milo D. Glenn Research Center AEROACOUSTICS; COAXIAL FLOW; GAS JETS; JET AIRCRAFT NOISE; NOISE PREDICTION (AIRCRAFT); NOISE REDUCTION; SUPERSONIC JET FLOW; COMPUTATIONAL FLUID DYNAMICS; FLOW STABILITY; MACH NUMBER; MIXING LENGTH FLOW THEORY; TEMPERATURE RATIO; VELOCITY DISTRIBUTION...
Aeroacoustics Jet Noise Combustion And Core Engine Noise
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Author : Ira R. Schwartz
language : en
Publisher:
Release Date : 1976
Aeroacoustics Jet Noise Combustion And Core Engine Noise written by Ira R. Schwartz and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1976 with Jet planes categories.
Aeroacoustics Of Turbulent High Speed Jets
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-06-30
Aeroacoustics Of Turbulent High Speed Jets written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-30 with categories.
Aeroacoustic noise generation in a supersonic round jet is studied to understand in particular the effect of turbulence structure on the noise without numerically compromising the turbulence itself. This means that direct numerical simulations (DNS's) are needed. In order to use DNS at high enough Reynolds numbers to get sufficient turbulence structure we have decided to solve the temporal jet problem, using periodicity in the direction of the jet axis. 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. Therefore in order to answer some questions about the turbulence we will partially compromise the overall structure of the jet. The first section of chapter 1 describes some work on the linear stability of a supersonic round jet and the implications of this for the jet noise problem. In the second section we present preliminary work done using a TVD numerical scheme on a CM5. This work is only two-dimensional (plane) but shows very interesting results, including weak shock waves. However this is a nonviscous computation and the method resolves the shocks by adding extra numerical dissipation where the gradients are large. One wonders whether the extra dissipation would influence small turbulent structures like small intense vortices. The second chapter is an extensive discussion of preliminary numerical work using the spectral method to solve the compressible Navier-Stokes equations to study turbulent jet flows. The method uses Fourier expansions in the azimuthal and streamwise direction and a 1-D B-spline basis representation in the radial direction. The B-spline basis is locally supported and this ensures block diagonal matrix equations which are solved in O(N) steps. A very accurate highly resolved DNS of a turbulent jet flow is expected. Rao, Ram Mohan and Lundgren, Thomas S. Ames Research Center NCC2-5017; DAAL03-89-C-0038...
Some Aspects Of The Aeroacoustics Of High Speed Jets
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Author : National Aeronautics and Space Adm Nasa
language : en
Publisher: Independently Published
Release Date : 2018-10-26
Some Aspects Of The Aeroacoustics Of High Speed Jets written by National Aeronautics and Space Adm Nasa and has been published by Independently Published this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-10-26 with Science categories.
Some of the background to contemporary jet aeroacoustics is addressed. Then scaling laws for noise generation by low-Mach-number airflows and by turbulence convected at 'not so low' Mach number is reviewed. These laws take into account the influence of Doppler effects associated with the convection of aeroacoustic sources. Next, a uniformly valid Doppler-effect approximation exhibits the transition, with increasing Mach number of convection, from compact-source radiation at low Mach numbers to a statistical assemblage of conical shock waves radiated by eddies convected at supersonic speed. In jets, for example, supersonic eddy convection is typically found for jet exit speeds exceeding twice the atmospheric speed of sound. The Lecture continues by describing a new dynamical theory of the nonlinear propagation of such statistically random assemblages of conical shock waves. It is shown, both by a general theoretical analysis and by an illustrative computational study, how their propagation is dominated by a characteristic 'bunching' process. That process associated with a tendency for shock waves that have already formed unions with other shock waves to acquire an increased proneness to form further unions - acts so as to enhance the high-frequency part of the spectrum of noise emission from jets at these high exit speeds. Lighthill, James Unspecified Center NAS1-19480; RTOP 50-90-52-01
Computational Aeroacoustics And Numerical Simulation Of Supersonic Jets
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Author : National Aeronautics and Space Administration (NASA)
language : en
Publisher: Createspace Independent Publishing Platform
Release Date : 2018-06-30
Computational Aeroacoustics And Numerical Simulation Of Supersonic Jets written by National Aeronautics and Space Administration (NASA) and has been published by Createspace Independent Publishing Platform this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-30 with categories.
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...
Aeroacoustics Of Flight Vehicles
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Author : Harvey H. Hubbard
language : en
Publisher:
Release Date : 1991
Aeroacoustics Of Flight Vehicles written by Harvey H. Hubbard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1991 with Aerodynamic noise categories.
Jet Aeroacoustics
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Author : Ganesh Raman
language : en
Publisher: Multi-Science Publishing Company
Release Date : 2008
Jet Aeroacoustics written by Ganesh Raman and has been published by Multi-Science Publishing Company this book supported file pdf, txt, epub, kindle and other format this book has been release on 2008 with Science categories.
An up-to-date survey of airplane noise, this single-volume reference thoroughly addresses the key problems facing aeronautical engineers. By tackling the most important aspects of jet aeroacoustics, including theories of jet noise, the design of jet noise facilities, and how jet noise is measured, this thoroughly researched analysis outlines a plan for first limiting the current distress being vocalized in issues of passenger cabin comfort and protests by those living near airports and later for finding an overall solution to jet noise.
Recent Advances In Aeroacoustics
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Author : A. Krothapalli
language : en
Publisher: Springer Science & Business Media
Release Date : 2012-12-06
Recent Advances In Aeroacoustics written by A. Krothapalli and has been published by Springer Science & Business Media this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-06 with Science categories.
The Joint Institute for Aeronautics and Acoustics at Stanford University was established in October 1973 to provide an academic environment for long-term cooperative research between Stanford and NASA Ames Research Center. Since its establishment, the Institute has conducted theoretical and experimental work in the areas of aerodynamics, acoustics, fluid mechanics, flight dynamics, guidance and control, and human factors. This research has involved Stanford faculty, research associates, graduate students, and many distinguished visitors in collaborative efforts with the research staff of NASA Ames Research Center. The occasion of the Institute's tenth anniversary was used to reflect back on where that research has brought us, and to consider where our endeavors should be directed next. Thus, an International Symposium was held to review recent advances in the fields relevant to the activities of the Institute and to discuss the areas of research to be undertaken in the future. This anniversary was also chosen as an opportunity to honor one of the Institute's founders and its director, Professor Krishnamurty Karamcheti. It has been his crea tive inspiration that has provided the ideal research environment at the Joint Institute.
Aeroacoustic Data For High Reynolds Number Supersonic Axisymmetric Jets
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Author : John M. Seiner
language : en
Publisher:
Release Date : 1985
Aeroacoustic Data For High Reynolds Number Supersonic Axisymmetric Jets written by John M. Seiner and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with Air jets categories.
Aeroacoustic Data For High Reynolds Number Supersonic Axisymmetric Jets
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Author :
language : en
Publisher:
Release Date : 1985
Aeroacoustic Data For High Reynolds Number Supersonic Axisymmetric Jets written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1985 with categories.