Aeroacoustics of low mach number flows : fundamentals, analysis and measurement / Stewart Glegg, William Devenport.

Format:

Book

Author/Creator:

Glegg, Stewart, author.

Devenport, William, author.

Language:

English

Subjects (All):

Aerodynamics--Mathematical models.

Aerodynamics.

Physical Description:

1 online resource (554 pages) : color illustrations, tables

Edition:

First edition.

Place of Publication:

London, England : Academic Press, 2017.

System Details:

text file

Summary:

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

Contents:

Front Cover

Aeroacoustics of Low Mach Number Flows Fundamentals, Analysis, and Measurement

Copyright

Dedication

Contents

Preface

Part 1: Fundamentals

Chapter 1: Introduction

1.1. Aeroacoustics of low Mach number flows

1.2. Sound waves and turbulence

1.3. Quantifying sound levels and annoyance

1.4. Symbol and analysis conventions used in this book

Chapter 2: The equations of fluid motion

2.1. Tensor notation

2.2. The equation of continuity

2.3. The momentum equation

2.3.1. General considerations

2.3.2. Viscous stresses

2.4. Thermodynamic quantities

2.5. The role of vorticity

2.5.1. Crocco's equation

2.5.2. The vorticity equation

2.5.3. The speed of sound in ideal flow

2.6. Energy and acoustic intensity

2.6.1. The energy equation

2.6.2. Sound power

2.7. Some relevant fluid dynamic concepts and methods

2.7.1. Streamlines and vorticity

2.7.2. Ideal flow

2.7.3. Conformal mapping

2.7.4. Vortex filaments and the Biot Savart law

Chapter 3: Linear acoustics

3.1. The acoustic wave equation

3.2. Plane waves and spherical waves

3.3. Harmonic time dependence

3.4. Sound generation by a small sphere

3.5. Sound scattering by a small sphere

3.6. Superposition and far field approximations

3.7. Monopole, dipole, and quadrupole sources

3.8. Acoustic intensity and sound power output

3.9. Solution to the wave equation using Green's functions

3.10. Frequency domain solutions and Fourier transforms

Chapter 4: Lighthill's acoustic analogy

4.1. Lighthill's analogy

4.2. Limitations of the acoustic analogy

4.2.1. Nearly incompressible flow

4.2.2. Uniform flow

4.3. Curle's theorem

4.4. Monopole, dipole, and quadrupole sources

4.5. Tailored Green's functions

4.6. Integral formulas for tailored Green's functions.

4.7. Wavenumber and Fourier transforms

Chapter 5: The Ffowcs Williams and Hawkings equation

5.1. Generalized derivatives

5.2. The Ffowcs Williams and Hawkings equation

5.3. Moving sources

5.4. Sources in a free stream

5.5. Ffowcs Williams and Hawkings surfaces

5.6. Incompressible flow estimates of acoustic source terms

Chapter 6: The linearized Euler equations

6.1. Goldstein's equation

6.2. Drift coordinates

6.3. Rapid distortion theory

6.4. Acoustically compact thin airfoils and the Kutta condition

6.5. The Prantl-Glauert transformation

Chapter 7: Vortex sound

7.1. Theory of vortex sound

7.2. Sound from two line vortices in free space

7.3. Surface forces in incompressible flow

7.4. Aeolian tones

7.5. Blade vortex interactions in incompressible flow

7.6. The effect of angle of attack and blade thickness on unsteady loads

7.6.1. The effect of angle of attack

7.6.2. The effect of airfoil thickness

Chapter 8: Turbulence and stochastic processes

8.1. The nature of turbulence

8.2. Averaging and the expected value

8.3. Averaging of the governing equations and computational approaches

8.4. Descriptions of turbulence for aeroacoustic analysis

8.4.1. Time correlations and frequency spectra of a single variable

8.4.2. Time correlations and frequency spectra of two variables

8.4.3. Spatial correlation and the wavenumber spectrum

Chapter 9: Turbulent flows

9.1. Homogeneous isotropic turbulence

9.1.1. Mathematical description

9.1.2. The von Kármán spectrum

9.1.3. The Liepmann spectrum

9.2. Inhomogeneous turbulent flows

9.2.1. The fully developed plane wake

9.2.2. The zero pressure gradient turbulent boundary layer

9.2.3. The turbulent boundary layer wall-pressure spectrum

Part 2: Experimental approaches.

Chapter 10: Aeroacoustic testing and instrumentation

10.1. Aeroacoustic wind tunnels

10.2. Wind tunnel acoustic corrections

10.2.1. Shear layer refraction

10.2.2. Corrections for a two-dimensional planar jet

10.2.3. Effects of shear layer thickness and curvature

10.2.4. Considerations for hybrid anechoic tunnels

10.3. Sound measurement

10.4. The measurement of turbulent pressure fluctuations

10.5. Velocity measurement

Chapter 11: Measurement, signal processing, and uncertainty

11.1. Limitations of measured data

11.2. Uncertainty

11.3. Averaging and convergence

11.4. Numerically estimating Fourier transforms

11.5. Measurement as seen from the frequency domain

11.6. Calculating time spectra and correlations

11.6.1. Calculating spectra

11.6.2. Uncertainty estimates

11.6.3. Phase spectra

11.6.4. Correlation functions

11.7. Wavenumber spectra and spatial correlations

Chapter 12: Phased arrays

12.1. Basic delay and sum processing

12.1.1. Basic principles, resolution, and spatial aliasing

12.1.2. Beam steering

12.1.3. Acoustic images and source levels

12.1.4. Array shading

12.1.5. Broadband noise sources

12.2. General approach to array processing

12.2.1. Background

12.2.2. The definition of source strength

12.2.3. Source images and the point spread function

12.2.4. Steering vectors

12.2.5. Signal-to-noise ratio

12.2.6. Array design

12.2.7. Array-processing algorithms

12.3. Deconvolution methods

12.3.1. Source spectra

12.3.2. The DAMAS method

12.3.3. The CLEAN algorithm

12.3.4. Integrated source maps

12.4. Correlated sources and directionality

Part 3: Edge and boundary layer noise

Chapter 13: The theory of edge scattering

13.1. The importance of edge scattering.

13.2. The Schwartzschild problem and its solution based on the Weiner Hopf method

13.2.1. The boundary value problem

13.2.2. Obtaining the Schwartzschild solution using the Weiner Hopf method

13.2.3. The radiation condition and the Weiner Hopf separation

13.2.4. Generalized Fourier transforms and Laplace transforms

13.3. The effect of uniform flow

13.4. The leading edge scattering problem

13.4.1. The leading edge response

13.4.2. The trailing edge correction

Chapter 14: Leading edge noise

14.1. The compressible flow blade response function

14.1.1. The compressible and incompressible flow blade response to a step gust

14.1.2. Leading and trailing edge solutions

14.1.3. The first-order solution for the surface pressure

14.1.4. The unsteady lift in compressible flow

14.1.5. An arbitrary gust

14.2. The acoustic far field

14.2.1. The acoustic far field from the leading edge interaction

14.2.2. The far-field directionality and scaling

14.2.3. Impulsive gusts of finite span

14.2.4. A step gust

14.3. An airfoil in a turbulent stream

14.4. Blade vortex interactions in compressible flow

14.4.1. The upwash velocity spectrum from a blade vortex interaction

Chapter 15: Trailing edge and roughness noise

15.1. The origin and scaling of trailing edge noise

15.2. Amiet's trailing edge noise theory

15.3. The method of Brooks, Pope, and Marcolini [8]

15.4. Roughness noise

Part 4: Rotating blades and duct acoustics

Chapter 16: Open rotor noise

16.1. Tone and broadband noise

16.2. Time domain prediction methods for tone noise

16.2.1. Loading noise

16.2.2. Thickness noise

16.2.3. Supersonic tip speeds

16.3. Frequency domain prediction methods for tone noise

16.3.1. Harmonic analysis of loading and thickness noise

16.4. Broadband noise from open rotors.

16.5. Haystacking of broadband noise

16.5.1. Amplitude modulation

16.5.2. Blade-to-blade correlation

16.6. Blade vortex interactions

Chapter 17: Duct acoustics

17.1. Introduction

17.2. The sound in a cylindrical duct

17.2.1. General formulation

17.2.2. Hard-walled ducts

17.2.3. Modal propagation

17.3. Duct liners

17.4. The Green's function for a source in a cylindrical duct

17.5. Sound power in ducts

17.6. Nonuniform mean flow

17.7. The radiation from duct inlets and exits

Chapter 18: Fan noise

18.1. Sources of sound in ducted fans

18.2. Duct mode amplitudes

18.2.1. Thickness noise for a ducted fan

18.2.2. Blade loading noise

18.2.3. Fan tone noise

18.2.4. In duct sound power

18.3. The cascade blade response function

18.3.1. The rectilinear cascade model

18.3.2. The acoustic duct modes

18.3.3. The acoustic modes from an arbitrary gust

18.3.4. The sound power spectrum

18.4. The rectilinear model of a rotor or stator in a cylindrical duct

18.4.1. Mode matching

18.4.2. An axial dipole example

18.5. Wake evolution in swirling flows

18.6. Fan tone noise

18.6.1. The upwash coefficients

18.6.2. Unskewed self-similar wakes

18.7. Broadband fan noise

Appendix A

A.1. Symbol conventions, symbol modifiers, and Fourier transforms

A.2. Symbols used

Appendix B

Appendix C

Index

Back Cover

Lighthill's acoustic analogy

Lighthill's analogy

Limitations of the acoustic analogy

Nearly incompressible flow

Uniform flow

Curle's theorem

Monopole, dipole, and quadrupole sources

Tailored Green's functions

Integral formulas for tailored Green's functions

Wavenumber and Fourier transforms

Vortex sound

Theory of vortex sound

Sound from two line vortices in free space

Surface forces in incompressible flow.

Aeolian tones.

Notes:

Includes bibliographical references at the end of each chapters and index.

Description based on print version record.

OCLC:

986540205