Noise Sources In Turbulent Shear Flows Fundamentals And Applications
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Noise Sources In Turbulent Shear Flows Fundamentals And Applications
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Author : Roberto Camussi
language : en
Publisher: Springer Science & Business Media
Release Date : 2013-02-11
Noise Sources In Turbulent Shear Flows Fundamentals And Applications written by Roberto Camussi 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 2013-02-11 with Technology & Engineering categories.
The articles in this volume present the state-of-the-art in noise prediction, modeling and measurement. The articles are partially based on class notes provided during the course `Noise sources in turbulent shear flows', given at CISM on April 2011. The first part contains general concepts of aero acoustics, including vortex sound theory and acoustic analogies, in the second part particular emphasis is put into arguments of interest for engineers and relevant for aircraft design: jet noise, airfoil broadband noise, boundary layer noise (including interior noise and its control) and the concept of noise sources, their theoretical modeling and identification in turbulent lows. All these arguments are treated extensively with the inclusion of many practical examples and references to engineering applications.
Mechanics Of Flow Induced Sound And Vibration Volume 1
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Author : William K. Blake
language : en
Publisher: Academic Press
Release Date : 2017-06-13
Mechanics Of Flow Induced Sound And Vibration Volume 1 written by William K. Blake and has been published by Academic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-06-13 with Technology & Engineering categories.
Mechanics of Flow-Induced Sound and Vibration, Volume 1: General Concepts and Elementary Sources, Second Edition, enables readers to fully understand flow-induced vibration and sound, unifying the disciplines of fluid dynamics, structural dynamics, vibration, acoustics, and statistics in order to classify and examine each of the leading sources of vibration and sound induced by various types of fluid motion. Starting with classical theories of aeroacoustics and hydroacoustics, a formalism of integral solutions valid for sources near boundaries is developed and then broadened to address different source types, including jet noise, flow tones, dipole sound from cylinders, and cavitation noise. Step-by-step derivations clearly identify any assumptions made throughout. Each chapter is illustrated with comparisons of leading formulas and measured data. Along with its companion, Mechanics of Flow-Induced Sound and Vibration, Volume 2: Complex Flow-Structure Interactions, the book covers everything an engineer needs to understand flow-induced sound and vibration. This book will be essential reading for postgraduate students, and for engineers and researchers with an interest in aerospace, ships and submarines, offshore structures, construction, and ventilation. Presents every important topic in flow-induced sound and vibration Covers all aspects of the topics addressed, from fundamental theory, to the analytical formulas used in practice Provides the building blocks of computer modeling for flow-induced sound and vibration
Aeroacoustics Of Low Mach Number Flows
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Author : Stewart Glegg
language : en
Publisher: Elsevier
Release Date : 2023-09-26
Aeroacoustics Of Low Mach Number Flows written by Stewart Glegg and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-09-26 with Technology & Engineering categories.
Aeroacoustics of Low Mach Number Flows: Fundamentals, Analysis and Measurement, Second Edition provides a detailed introduction to sound radiation from subsonic flow over moving surfaces. This phenomenon is the most widespread cause of flow noise in engineering systems, including fan noise, rotor noise, wind turbine noise, boundary layer noise, airframe noise and aircraft noise. This fully updated new edition includes additional problems, illustrations and summary materials to support readers. New content covers Rapid Distortion theory (RDT), boundary layer wall pressure fluctuations, and flow induced sound at surfaces. Themes addressing non-compressible flows have also been added, offering coverage of hydroacoustic as well as aeroacoustic applications. New support materials for this edition include course outlines, problem sets, sample MATLAB codes and experimental data to be found at www.aeroacoustics.net. Addresses, in detail, sound from rotating blades, ducted fans, airframes, boundary layers, and more Presents theory in such a way that it can be used in computational methods and calculating sound levels Includes coverage of different experimental approaches to this subject
Flinovia Flow Induced Noise And Vibration Issues And Aspects Ii
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Author : Elena Ciappi
language : en
Publisher: Springer
Release Date : 2018-05-25
Flinovia Flow Induced Noise And Vibration Issues And Aspects Ii written by Elena Ciappi and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-05-25 with Technology & Engineering categories.
This is the proceedings of the Second International Workshop on Flow Induced Noise and Vibration (FLINOVIA), which was held in Penn State, USA, in April 2016. The authors’ backgrounds represent a mix of academia, government, and industry, and several papers include applications to important problems for underwater vehicles, aerospace structures and commercial transportation. The book offers a valuable reference guide for all those working in the area of flow-induced vibration and noise. Flow induced vibration and noise (FIVN) remains a critical research topic. Even after over 50 years of intensive research, accurate and cost-effective FIVN simulation and measurement techniques remain elusive. This book gathers the latest research from some of the most prominent experts in the field. The book describes methods for characterizing wall pressure fluctuations, including subsonic and supersonic turbulent boundary layer flows over smooth and rough surfaces using computational methods like Large Eddy Simulation; for inferring wall pressure fluctuations using inverse techniques based on panel vibrations or holographic pressure sensor arrays; for calculating the resulting structural vibrations and radiated sound using traditional finite element methods, as well as advanced methods like Energy Finite Elements; for using scaling approaches to universally collapse flow-excited vibration and noise spectra; and for computing time histories of structural response, including alternating stresses.
Proceedings Of Xxiv Aimeta Conference 2019
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Author : Antonio Carcaterra
language : en
Publisher: Springer Nature
Release Date : 2020-03-31
Proceedings Of Xxiv Aimeta Conference 2019 written by Antonio Carcaterra and has been published by Springer Nature this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-03-31 with Science categories.
This book gathers the peer-reviewed papers presented at the XXIV Conference of the Italian Association of Theoretical and Applied Mechanics, held in Rome, Italy, on September 15-19, 2019 (AIMETA 2019). The conference topics encompass all aspects of general, fluid, solid and structural mechanics, as well as mechanics for machines and mechanical systems, including theoretical, computational and experimental techniques and technological applications. As such the book represents an invaluable, up-to-the-minute tool, providing an essential overview of the most recent advances in the field.
Some Remarks On The Theory Of Noise Generation By Turbulent Shear Flows
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Author : Wiktor Eckhaus
language : en
Publisher:
Release Date : 1960
Some Remarks On The Theory Of Noise Generation By Turbulent Shear Flows written by Wiktor Eckhaus and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1960 with Turbulence categories.
Fundamentals Of Aeroacoustics With Applications To Aeropropulsion Systems
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Author : Xiaofeng Sun
language : en
Publisher: Elsevier
Release Date : 2020-10-14
Fundamentals Of Aeroacoustics With Applications To Aeropropulsion Systems written by Xiaofeng Sun and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2020-10-14 with Technology & Engineering categories.
Fundamentals of Aeroacoustics with Applications to Aeropropulsion Systems from the Shanghai Jiao Tong University Press Aerospace series, is the go-to reference on the topic, providing a modern take on the fundamental theory and applications relating to prediction and control of all major noise sources in aeropropulsion systems. This important reference compiles the latest knowledge and research advances, considering both the physics of aerodynamic noise generation in aero-engines and related numerical prediction techniques. Additionally, it introduces new vortex sound interaction models, a transfer element method, and a combustion instability model developed by the authors. Focusing on propulsion systems from inlet to exit, including combustion noise, this new resource will aid graduate students, researchers, and R&D engineers in solving the aircraft noise problems that currently challenge the industry. Updates the knowledge-base on the sound source generated by aeropropulsion systems, from inlet to exit, including combustion noise Covers new aerodynamic noise control technology aimed at the low-noise design of next generation aero-engines, including topics such as aerodynamic noise and aero-engine noise control Includes new, cutting-edge models and methods developed by an author team led by the editor-in-chief of the Chinese Journal of Aeronautics and Astronautics Considers both the physics of aerodynamic noise generation in aero-engines and related numerical prediction techniques
Study Of Jet Exhaust Noise Sources And Their Mitigation Through Lobed Mixers And Chevrons
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Author : Danielle Grage
language : en
Publisher:
Release Date : 2011
Study Of Jet Exhaust Noise Sources And Their Mitigation Through Lobed Mixers And Chevrons written by Danielle Grage and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2011 with categories.
As regulations to reduce noise pollution become more stringent, understanding the noise sources within jet exhaust and how they can be mitigated is important as jet noise is one of the dominant contributors to the overall acoustic signature of an engine. The objective of this study is to understand the effects two exhaust mixing devises, lobed mixers and chevrons. To this end, three basic configurations were studied: a confluent mixer and nozzle (Confluent), a buried lobed mixer with a circular nozzle (MixerA), and a buried lobed mixer with a chevron nozzle (Chevron+MixerB). The hardware was tested at GE Aviation's Cell-41 - Anechoic free jet facility. Acoustic data was acquired, as well as flowfield data using Particle Image Velocimetry (PIV). RANS-based (Reynolds Averaged Navier-Stokes) Computational Fluid Dynamics (CFD) analyses were also conducted to complement the test data. Three operating conditions were considered, defined by their shear level, which is a function of the average mixed velocity of the core flow: low shear (80%), nominal shear (100%), and high shear (112%). The results from the PIV and CFD were used for mutual validation and very good correlation was observed for the MixerA configuration with good correlation overall. The acoustic results were consistent with the flowfield analysis, as well as previous studies, and showed that the presence of mixing devices can provide a low frequency acoustic benefit with some modest increase in high frequency noise, due to increasing mixing near the nozzle and reduced turbulence downstream. An additional high frequency noise source was also identified for MixerA at the high shear condition, which was not present for other configurations. This source showed similar features to the High Mach Lift (HML) previously reported by Tester et al and Garrison et al in 2005. It is thought to be the result of shear layer interaction with a normal shock, resulting from localized pockets of supersonic flow that form near the nozzle exit plane. This source was absent for the Chevron+MixerB configuration and more work must be done to better understand the phenomenon.
An Experimental Investigation Of The Influence Of Air Bubbles On The Acoustic Radiation Efficiency Of Turbulent Shear Flow
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Author : Roger E. A. Arndt
language : en
Publisher:
Release Date : 1987
An Experimental Investigation Of The Influence Of Air Bubbles On The Acoustic Radiation Efficiency Of Turbulent Shear Flow written by Roger E. A. Arndt and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1987 with categories.
Jet Noise Source Localization And Identification
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Author : Unnikrishnan Sasidharan Nair
language : en
Publisher:
Release Date : 2017
Jet Noise Source Localization And Identification written by Unnikrishnan Sasidharan Nair and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.
The exact mechanism by which turbulent fluctuations in jets are converted into acoustic energy remains unexplained. The current work aims to improve our understanding of this problem by localizing acoustic sources and identifying its causal dynamics. We use Large-Eddy Simulations of a Mach 1.3 turbulent cold jet for this purpose. The localization question is resolved by using a novel technique, termed Synchronous Large-Eddy Simulations (SLES), that tracks the non-linear evolution of small perturbations from any region (window) in a time-varying base flow. This provides superior insights into the generation of intermittency and directivity compared to traditional approaches that use linear stability analyses based on steady basic states or backward correlations between different regions of the flow. In SLES, two simulations are performed in a lock-step manner. At each step, native fluctuations from a desired spatial window in the first (or baseline simulation) are scaled to small values and then injected into the second (or twin simulation) to provide a forcing in the targeted region. At subsequent times, the difference between the two simulations provides a snapshot of the evolution of the perturbation field associated with the continuous forcing in the chosen spatial window. The perturbation field, which is equivalent to the solution of the forced Navier-Stokes equations linearized about the time-evolving base flow, is then statistically analyzed to identify its modulation by the turbulent region of the jet. Results are distilled by examining forcing at lipline and centerline locations in detail. The end of the potential core is found to be a sensitive zone where perturbations are amplified and lead to secondary sources. Perturbations within the shear layer on the other hand, are initially channeled toward the core and undergo higher amplification compared to those originating from the centerline, before propagating outward. Statistical analyses quantify intermittent events which have a major role in creating the nearfield sound signature and yield polar variation of the most significant frequency band. The flowfield is decomposed into its acoustic, hydrodynamic and thermal modes (which are referred to as the Fluid-Thermodynamic (FT) modes) using the Momentum Potential Theory to identify the acoustic sources and extract the propagated field of the jet. The hydrodynamic mode highlights the shear layer roll up and turbulent mixing, while the acoustic and thermal modes exhibit a wavepacket nature in the core. The acoustic wavepacket develops into the nearfield radiation pattern of the jet, with spatio-temporal amplifications in the core due to the presence of vorticity resulting in nearfield intermittent events. The acoustic and hydrodynamic modes closely follow the theoretical decay rates and the former possess the features of experimentally observed model sound spectra along the downstream and sideline polar angles. Inter-modal energy transfers in the non-linear flow are analyzed using the transport equation for the universal acoustic variable, Total Fluctuating Enthalpy (TFE). Production terms of TFE identify intruding vortices in the potential core as the principal physical mechanism by which intermittent acoustic sources are generated in the jet. The acoustic wavepacket and its nearfield fluctuations play a central role in transporting TFE utward from the core, resulting in the near and farfield sound signature of the jet. The present work provides unique insights into time-accurate linear response of a turbulent jet, and quantifies the relative prominence of various core locations in generating the nearfield acoustic signature. The evolution of the linear perturbation field highlights the modulation of random turbulent fluctuations into spatio-temporally persistent intermittent events. While the intermediate frequencies in the jet propagate in the upstream direction, the highest and lowest frequency-bands prevail in the sideline and downstream directions respectively. The FT mode decomposition elucidates the energy transfer mechanisms in the jet. It provides a phenomenological model to explain the amplification of the acoustic mode, leading to intermittent sound events in the nearfield as well as generation of acoustic sources. The FT modes also quantify the net energy flux scattered and transmitted out of the jet, delineating the stochastic turbulence from a relatively orderly acoustic transport.