Skip to main content

Aeroacoustics Of Low Mach Number Flows

In Order to Read Online or Download Aeroacoustics Of Low Mach Number Flows Full eBooks in PDF, EPUB, Tuebl and Mobi you need to create a Free account. Get any books you like and read everywhere you want. Fast Download Speed ~ Commercial & Ad Free. We cannot guarantee that every book is in the library!

Aeroacoustics of Low Mach Number Flows

Aeroacoustics of Low Mach Number Flows Book
Author : Stewart Glegg,William Devenport
Publisher : Academic Press
Release : 2017-02-15
ISBN : 0128097930
Language : En, Es, Fr & De

GET BOOK

Book Description :

Aeroacoustics of Low Mach Number Flows: Fundamentals, Analysis, and Measurement provides a comprehensive treatment of sound radiation from subsonic flow over moving surfaces, which is the most widespread cause of flow noise in engineering systems. This includes fan noise, rotor noise, wind turbine noise, boundary layer noise, and aircraft noise. Beginning with fluid dynamics, the fundamental equations of aeroacoustics are derived and the key methods of solution are explained, focusing both on the necessary mathematics and physics. Fundamentals of turbulence and turbulent flows, experimental methods and numerous applications are also covered. The book is an ideal source of information on aeroacoustics for researchers and graduate students in engineering, physics, or applied math, as well as for engineers working in this field. Supplementary material for this book is provided by the authors on the website www.aeroacoustics.net. The website provides educational content designed to help students and researchers in understanding some of the principles and applications of aeroacoustics, and includes example problems, data, sample codes, course plans and errata. The website is continuously being reviewed and added to. Explains the key theoretical tools of aeroacoustics, from Lighthill’s analogy to the Ffowcs Williams and Hawkings equation Provides detailed coverage of sound from lifting surfaces, boundary layers, rotating blades, ducted fans and more Presents the fundamentals of sound measurement and aeroacoustic wind tunnel testing

Aeroacoustics of Low Mach Number Flows

Aeroacoustics of Low Mach Number Flows Book
Author : Stewart Glegg,William Devenport
Publisher : Unknown
Release : 2017
ISBN : 0987650XXX
Language : En, Es, Fr & De

GET BOOK

Book Description :

Aeroacoustics of Low Mach Number Flows: Fundamentals, Analysis, and Measurement provides a comprehensive treatment of sound radiation from subsonic flow over moving surfaces, which is the most widespread cause of flow noise in engineering systems. This includes fan noise, rotor noise, wind turbine noise, boundary layer noise, and aircraft noise. Beginning with fluid dynamics, the fundamental equations of aeroacoustics are derived and the key methods of solution are explained, focusing both on the necessary mathematics and physics. Fundamentals of turbulence and turbulent flows, experimental methods and numerous applications are also covered. The book is an ideal source of information on aeroacoustics for researchers and graduate students in engineering, physics, or applied math, as well as for engineers working in this field. Supplementary material for this book is provided by the authors on the website www.aeroacoustics.net. The website provides educational content designed to help students and researchers in understanding some of the principles and applications of aeroacoustics, and includes example problems, data, sample codes, course plans and errata. The website is continuously being reviewed and added to. Explains the key theoretical tools of aeroacoustics, from Lighthill's analogy to the Ffowcs Williams and Hawkings equation Provides detailed coverage of sound from lifting surfaces, boundary layers, rotating blades, ducted fans and more Presents the fundamentals of sound measurement and aeroacoustic wind tunnel testing.

Computational Aeroacoustics in Low Mach Number Flows

Computational Aeroacoustics in Low Mach Number Flows Book
Author : Pradera-Mallabiabarrena Ainara
Publisher : LAP Lambert Academic Publishing
Release : 2015-08-10
ISBN : 9783659768378
Language : En, Es, Fr & De

GET BOOK

Book Description :

This work studies a flexible methodology to predict radiated noise. The main contributions of this work are focused on the way flow parameters are acquired in fluid dynamics simulations are synthesised, stored and later used to predict radiated noise, but also on the procedure considered in the radiation calculations. The methodology has been restricted to low Mach number flows where the noise generation is dominated by the interaction of the flow with a surface at least one of whose typical dimensions is short compared to the wavelength of intereset, known as a compact source. The radiation calculations may employ purely analytical methods or numerical methods, depending on the application. Finally, the requirements in data storage and transfer are significantly reduced by using this method. Besides, if the flow remains essentially the same, the Computational Fluid Dynamics simulation should not need to be repeated in case different acoustic scenarios should be studied.

Wall Cavity Aeroacoustics at Low Mach Number

Wall Cavity Aeroacoustics at Low Mach Number Book
Author : Anonim
Publisher : Unknown
Release : 2004
ISBN : 0987650XXX
Language : En, Es, Fr & De

GET BOOK

Book Description :

Theoretical and numerical analyses are made of the mechanism of sound production by nominally steady low Mach number flow over a rigid shallow wall cavity. At very low Mach numbers the dominant source of sound is the unsteady drag, and the aeroacoustic dipole source accompanying this force. A monopole source dependent on the compression of fluid within the cavity is smaller by a factor of the order of the flow Mach number M. However, numerical simulations for M as small as 0.1 have predicted significant radiation in directions normal to the wall. This anomaly is investigated by using an acoustic Green's function tailored to cavity geometry. The Green's function is extended to examine the production of sound by vortex shedding at lock-on' from a cross-beam adjacent.

Aeroacoustic Computation of Low Mach Number Flow

Aeroacoustic Computation of Low Mach Number Flow Book
Author : Kristian Skriver Dahl
Publisher : Unknown
Release : 1996
ISBN : 9788755022492
Language : En, Es, Fr & De

GET BOOK

Book Description :

Download Aeroacoustic Computation of Low Mach Number Flow book written by Kristian Skriver Dahl, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Topics in Hyposonic Flow Theory

Topics in Hyposonic Flow Theory Book
Author : Radyadour Kh. Zeytounian
Publisher : Springer Science & Business Media
Release : 2005-12-20
ISBN : 9783540255499
Language : En, Es, Fr & De

GET BOOK

Book Description :

Hyposonic fluid flows, characterized by a low Mach number, are mainly linked with geophysical and environmental fluid flows. In addition they are relevant to engineers because of their connection with aerodynamics. The books brings together insights derived from mathematically rigorous results and combines them with a number of realistic fluid flow situations. Asymptotic analytic solutions for the low-Mach number cases are developed to provide both insights into the underlying physics as well as benchmarks for numerical computations.

Aeroacoustic Computation of Tones Generated from Low Mach Number Cavity Flows Using a Preconditioned Method

Aeroacoustic Computation of Tones Generated from Low Mach Number Cavity Flows  Using a Preconditioned Method Book
Author : Brent Paul
Publisher : Unknown
Release : 2016
ISBN : 0987650XXX
Language : En, Es, Fr & De

GET BOOK

Book Description :

The hydrodynamically generated noise produced from flow over cavities includes both broadband and tones. The frequency content and amplitude of the resulting noise is a function of the cavity geometry and the approaching boundary layer. The cavity length to depth ratio (L/D) is an important parameter that governs the characteristics of cavity noise generated. While both of the noise components are important this work will focus on the production of cavity tones. Cavity tones typically have higher sound pressure levels and can propagate over longer distances than the broadband noise.The enhancements to the numerical code shown in this work result in the first non-hybrid tool for the prediction of low speed cavity noise. At moderate subsonic Mach numbers the direct calculation of cavity tones has been performed by numerous researchers using highly accurate spatial and time discretization. However, most researchers that are trying to predict the noise from low Mach number flows take a hybrid approach where the fluid dynamics of the simulation are solved with a computational fluid dynamics (CFD) solver and the acoustics are solved separately. The other solver is often based on Lighthills Acoustic Analogy or an asympototic method such as the Expansion about Incompressible Flow (EIF). This work calculates the conservative Navier-Stokes variables to directly predict the cavity tones.The numerical solver CHOPA (Compressible, High-Order Parallel Acoustics) is extended in this work for the accurate and fast calculation of low Mach number cavity flows. A time-derivative preconditioner equalizes the acoustic wave and turbulence convective speeds to allow for a more efficient time step and shorter calculation times. Because the preconditioner destroys the time accuracy of the solution a dual-time step approach is used for the time integration. Other modifications to the code are required to facilitate the proper implementation of the preconditioner: Matrix-based artificial dissipation, buffer zone, and extrapolation boundary condition. An extension by Buelow of Choi-Merkles viscous preconditioner is selected for this work.There are several different numerical validations performed on the preconditioned Navier-Stokes solver to ensure high quality solutions. First, the combination buffer zone/extrapolation boundary condition is tested by simulating the propagation of a Gaussian pressure pulse. Then the preconditioner is tested with several different analyses. The convection of a uniform velocity flow field with a random perturbation imposed on the flow field tests if the preconditioned solution is independent of the flow Mach number. Then a time accurate Gaussian pressure pulse tests the ability of the preconditioner to solve a time dependent solution. Lastly, a laminar boundary layer flow is calculated and compared to an exact solution showing that the preconditioner is effective for viscous flows. The prediction of cavity tones from a deep (L/D = 0.78) and shallow (L/D = 2.35) cavity is simulated for comparison against the experimental measurements of Block. The Mach number of the simulations varied from 0.05 to 0.4. The cavity tone frequencies have an acceptable comparison against the measurements for the deep cavity. However, the shallow cavity tones were almost independent of the flow speed, which may be an indication that standing waves in the cavity could be responsible for the tones for this geometry. The other cavity simulations replicated the experiment by Stallings et al.for L/D = 5.42 and L/D = 6.25 for a Mach number of 0.2. The time-averaged wall pressure fluctuations were compared to measurements. While the predicted wall pressures did not match the experiment the discrepancy is because of the existence of a wake mode in the numerical results. This is a two-dimensional phenomenon where a large vortex is generated in the cavity and then violently ejected from the cavity, significantly increasing drag. While not matching the experiment the results behave as expected for a cavity resonating in a wake mode.

Computational Aeroacoustics of Complex Flows at Low Mach Number

Computational Aeroacoustics of Complex Flows at Low Mach Number Book
Author : Yaser Khalighi
Publisher : Unknown
Release : 2010
ISBN : 0987650XXX
Language : En, Es, Fr & De

GET BOOK

Book Description :

Designing quiet mechanical systems requires an understanding of the physics of sound generation. Among various sources of noise, aerodynamic sound is the most difficult component to mitigate. In practical applications, aerodynamic sound is generated by complex flow phenomena such as turbulent wakes and boundary layers, separation, and interaction of turbulent flow with irregular solid bodies. In addition, sound waves experience multiple reflections from solid bodies before they propagate to an observer. Prediction of an acoustic field in such configurations requires a general aeroacoustic framework to operate in complex configurations. A general computational aeroacoustics method is developed to evaluate noise generated by low Mach number flow in complex configurations. This method is a hybrid approach which uses Lighthill's acoustic analogy in conjunction with source-data from an incompressible calculation. Flow-generated sound sources are computed by using either direct numerical simulation (DNS) or large eddy simulation (LES); scattering of sound waves are computed using a boundary element method (BEM). In this approach, commonly-made assumptions about the geometry of scattering objects or frequency content of sound are not present, thus it can be applied to a wider range of aeroacoustic problems, where sound is generated by interaction of complex flows with solid surfaces. This new computational technique is applied to a variety of aeroacoustic problems ranging from sound generated by laminar and turbulent vortex shedding from cylinders to realistic configurations such as noise emitted from a rear-view side mirror and a hydrofoil. The purpose of each test case, in addition to validation of the method, is to explore various physical and technical aspects of the problem of sound generation by unsteady flows. Through these test cases, it is demonstrated that the predicted sound field by this technique is accurate in the frequency range in which the sound sources are resolved by the computational mesh. It is also shown that in computation of sound, acoustic analogies are less sensitive to numerical errors than direct computations. Finally, a discussion on the efficacy of LES and the effect of sub-grid scale dynamics on predicted sound is presented.

Asymptotic Modelling of Fluid Flow Phenomena

Asymptotic Modelling of Fluid Flow Phenomena Book
Author : Radyadour Kh. Zeytounian
Publisher : Springer Science & Business Media
Release : 2006-04-10
ISBN : 0306483866
Language : En, Es, Fr & De

GET BOOK

Book Description :

for the fluctuations around the means but rather fluctuations, and appearing in the following incompressible system of equations: on any wall; at initial time, and are assumed known. This contribution arose from discussion with J. P. Guiraud on attempts to push forward our last co-signed paper (1986) and the main idea is to put a stochastic structure on fluctuations and to identify the large eddies with a part of the probability space. The Reynolds stresses are derived from a kind of Monte-Carlo process on equations for fluctuations. Those are themselves modelled against a technique, using the Guiraud and Zeytounian (1986). The scheme consists in a set of like equations, considered as random, because they mimic the large eddy fluctuations. The Reynolds stresses are got from stochastic averaging over a family of their solutions. Asymptotics underlies the scheme, but in a rather loose hidden way. We explain this in relation with homogenizati- localization processes (described within the §3. 4 ofChapter 3). Ofcourse the mathematical well posedness of the scheme is not known and the numerics would be formidable! Whether this attempt will inspire researchers in the field of highly complex turbulent flows is not foreseeable and we have hope that the idea will prove useful.

Hyperbolic Partial Differential Equations

Hyperbolic Partial Differential Equations Book
Author : Andreas Meister,Jens Struckmeier
Publisher : Springer Science & Business Media
Release : 2012-12-06
ISBN : 3322802272
Language : En, Es, Fr & De

GET BOOK

Book Description :

The book gives an introduction to the fundamental properties of hyperbolic partial differential equations und their appearance in the mathematical modelling of various problems from practice. It shows in an unique manner concepts for the numerical treatment of such equations starting from basic algorithms up actual research topics in this area. The numerical methods discussed are central and upwind schemes for structured and unstructured grids based on ENO and WENO reconstructions, pressure correction schemes like SIMPLE and PISO as well as asymptotic-induced algorithms for low-Mach number flows.

Computational Aeroacoustics

Computational Aeroacoustics Book
Author : Jay C. Hardin,M.Y. Hussaini
Publisher : Springer Science & Business Media
Release : 2012-12-06
ISBN : 1461383420
Language : En, Es, Fr & De

GET BOOK

Book Description :

Computational aeroacoustics is rapidly emerging as an essential element in the study of aerodynamic sound. As with all emerging technologies, it is paramount that we assess the various opportuni ties and establish achievable goals for this new technology. Essential to this process is the identification and prioritization of fundamental aeroacoustics problems which are amenable to direct numerical siIn ulation. Questions, ranging from the role numerical methods play in the classical theoretical approaches to aeroacoustics, to the correct specification of well-posed numerical problems, need to be answered. These issues provided the impetus for the Workshop on Computa tional Aeroacoustics sponsored by ICASE and the Acoustics Division of NASA LaRC on April 6-9, 1992. The participants of the Work shop were leading aeroacousticians, computational fluid dynamicists and applied mathematicians. The Workshop started with the open ing remarks by M. Y. Hussaini and the welcome address by Kristin Hessenius who introduced the keynote speaker, Sir James Lighthill. The keynote address set the stage for the Workshop. It was both an authoritative and up-to-date discussion of the state-of-the-art in aeroacoustics. The presentations at the Workshop were divided into five sessions - i) Classical Theoretical Approaches (William Zorumski, Chairman), ii) Mathematical Aspects of Acoustics (Rodolfo Rosales, Chairman), iii) Validation Methodology (Allan Pierce, Chairman), iv) Direct Numerical Simulation (Michael Myers, Chairman), and v) Unsteady Compressible Flow Computa tional Methods (Douglas Dwoyer, Chairman).

Aeroacoustic Noise Generation for Low Mach Number Turbulent Flow

Aeroacoustic Noise Generation for Low Mach Number Turbulent Flow Book
Author : Federico Mattia Visconti
Publisher : Unknown
Release : 2007
ISBN : 0987650XXX
Language : En, Es, Fr & De

GET BOOK

Book Description :

Download Aeroacoustic Noise Generation for Low Mach Number Turbulent Flow book written by Federico Mattia Visconti, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Computational Acoustics

Computational Acoustics Book
Author : Manfred Kaltenbacher
Publisher : Springer
Release : 2017-08-08
ISBN : 3319590383
Language : En, Es, Fr & De

GET BOOK

Book Description :

The book presents a state-of-art overview of numerical schemes efficiently solving the acoustic conservation equations (unknowns are acoustic pressure and particle velocity) and the acoustic wave equation (pressure of acoustic potential formulation). Thereby, the different equations model both vibrational- and flow-induced sound generation and its propagation. Latest numerical schemes as higher order finite elements, non-conforming grid techniques, discontinuous Galerkin approaches and boundary element methods are discussed. Main applications will be towards aerospace, rail and automotive industry as well as medical engineering. The team of authors are able to address these topics from the engineering as well as numerical points of view.

Coanda Effect

Coanda Effect Book
Author : Noor A Ahmed
Publisher : CRC Press
Release : 2019-08-28
ISBN : 0429805446
Language : En, Es, Fr & De

GET BOOK

Book Description :

Coanda effect is a complex fluid flow phenomenon enabling the production of vertical take-off/landing aircraft. Other applications range from helicopters to road vehicles, from flow mixing to combustion, from noise reduction to pollution control, from power generation to robot operation, and so forth. Book starts with description of the effect, its history and general formulation of governing equations/simplifications used in different applications. Further, it gives an account of this effect’s lift boosting potential on a wing and in non-flying vehicles including industrial applications. Finally, occurrence of the same in human body and associated adverse medical conditions are explained.

Some Aspects of the Aeroacoustics of High Speed Jets

Some Aspects of the Aeroacoustics of High Speed Jets Book
Author : Institute for Computer Applications in Science and Engineering,James Lighthill
Publisher : Unknown
Release : 1993
ISBN : 0987650XXX
Language : En, Es, Fr & De

GET BOOK

Book Description :

The lecture begins by sketching some of the background to contemporary jet aeroacoustics. Then it reviews scaling laws for noise generation by low-Mach-number airflows and by turbulence convected at 'not so low' Mach number. 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 ... Jet acoustics, Nonlinear propagation, Conical shocks, Numerical experiments.

Recent Advances in Computational Engineering

Recent Advances in Computational Engineering Book
Author : Michael Schäfer,Marek Behr,Miriam Mehl,Barbara Wohlmuth
Publisher : Springer
Release : 2018-08-21
ISBN : 3319938916
Language : En, Es, Fr & De

GET BOOK

Book Description :

This book comprises the proceedings of the 4th International Conference on Computational Engineering (ICCE 2017), held in Darmstadt, Germany on September 28-29, 2017. The conference is intended to provide an interdisciplinary meeting place for researchers and practitioners working on computational methods in all disciplines of engineering, applied mathematics and computer science. The aims of the conference are to discuss the state of the art in this challenging field, exchange experiences, develop promising perspectives for future research and initiate further cooperation. Computational Engineering is a modern and multidisciplinary science for computer-based modeling, simulation, analysis, and optimization of complex engineering applications and natural phenomena. The book contains an overview of selected approaches from numerics and optimization of Partial Differential Equations as well as uncertainty quantification techniques, typically in multiphysics environments. Where possible, application cases from engineering are integrated. The book will be of interest to researchers and practitioners of Computational Engineering, Applied Mathematics, Engineering Sciences and Computer Science.

Some Aspects of the Aeroacoustics of High Speed Jets

Some Aspects of the Aeroacoustics of High Speed Jets Book
Author : National Aeronautics and Space Adm Nasa
Publisher : Independently Published
Release : 2018-10-26
ISBN : 9781729270028
Language : En, Es, Fr & De

GET BOOK

Book Description :

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

Flinovia Flow Induced Noise and Vibration Issues and Aspects III

Flinovia   Flow Induced Noise and Vibration Issues and Aspects III Book
Author : Elena Ciappi
Publisher : Springer Nature
Release : 2021-07-30
ISBN : 3030648079
Language : En, Es, Fr & De

GET BOOK

Book Description :

Download Flinovia Flow Induced Noise and Vibration Issues and Aspects III book written by Elena Ciappi, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.

Waves in Flows

Waves in Flows Book
Author : Tomáš Bodnár
Publisher : Springer Nature
Release : 2021-07-30
ISBN : 3030678458
Language : En, Es, Fr & De

GET BOOK

Book Description :

Download Waves in Flows book written by Tomáš Bodnár, available in PDF, EPUB, and Kindle, or read full book online anywhere and anytime. Compatible with any devices.