Mechanics of Flow-Induced Sound and Vibration, Volume 1

General Concepts and Elementary Sources

William K. Blake

• Publisher: Academic Press
• Year: 2017
• ISBN:
  9780128122891
• Edition: 2
• Topic: Physical Sciences
• Subtopic: Fluid Mechanics

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

Chapter 1

Introductory Concepts

Abstract

Sound may be emitted whenever a relative motion exists in fluids or between a fluid and a surface. The common physical processes that are responsible for noise generation include turbulent fluid motions, vibration of structures, acoustics, and aerodynamics of wings and bodies. The parameters of various forms of interaction must be known in order to effect productive design changes for noise control. This chapter introduces the concepts of noise generation through flow and body–flow interactions. The dimensional analysis of sound generation is introduced along with the importance of geometrical similitude in modelling. The practical results of signal analysis are described including the fundamentals of correlation analysis, Fourier analysis, and simple filtering theory. The established means of quantifying acoustic variables is discussed and an illustration of nondimensionalization is given. The chapter ends with a refresher of the mathematical operations and definitions that occur throughout the rest of the book including coordinate systems, differential operators, integral theorems, and the Dirac delta function.

Keywords

Acoustic intensity; array; auto correlation; auto spectral density; body-flow interactions; cross correlation; cross spectral density; decibel; Dirac delta; filter; spatial filter; Fourier transform; Kronecker delta; Laplacian operator; Mach number; nondimensional spectrum; nondimensionalization; periodic signals; proportional band level; quadrature spectrum; random signals; Reynolds number; signal analysis; sound intensity level; sound power level; sound pressure level; spectral density; transfer function; turbulence; vortex filament; vortex line; wave number

1.1 Occ...