Abstract
The thesis presents a numerical method developed by the author and its applications for computing the generated sound by an unsteady flow field and its propagation.
The full equations of motion for compressible and unsteady flows describe both flow field and sound generation and propagation. It is assumed that the flow variables can be decomposed into semicompressible / incompressible components and inviscid, irrotational acoustic components. The present method is based on Large Eddy Simulation (LES) to compute the turbulent flow and an approach based on an inhomogeneous wave equation to compute the radiated acoustic field. In this way one can avoid the necessity for a very large computational effort associated with direct simulation of the near and specially far field sound generated by a turbulent flow. The governing equations are written in the form of a nonhomogeneous wave equation for the acoustic fluctuation with acoustic sources on the righthand side. The thesis includes the details of the coupling between the flow solver and the acoustic one, as well as the results for test cases employed to validate the numerical algorithm and the implemented boundary conditions.
The method has been successfully applied to compute the near and far acoustic fields generated by various unsteady flows such as a round hot turbulent jet ejected from a pipe close to a solid boundary, coaxial turbulent nonisothermal jets (separate exhaust system), or the flow around a windturbine.
The full equations of motion for compressible and unsteady flows describe both flow field and sound generation and propagation. It is assumed that the flow variables can be decomposed into semicompressible / incompressible components and inviscid, irrotational acoustic components. The present method is based on Large Eddy Simulation (LES) to compute the turbulent flow and an approach based on an inhomogeneous wave equation to compute the radiated acoustic field. In this way one can avoid the necessity for a very large computational effort associated with direct simulation of the near and specially far field sound generated by a turbulent flow. The governing equations are written in the form of a nonhomogeneous wave equation for the acoustic fluctuation with acoustic sources on the righthand side. The thesis includes the details of the coupling between the flow solver and the acoustic one, as well as the results for test cases employed to validate the numerical algorithm and the implemented boundary conditions.
The method has been successfully applied to compute the near and far acoustic fields generated by various unsteady flows such as a round hot turbulent jet ejected from a pipe close to a solid boundary, coaxial turbulent nonisothermal jets (separate exhaust system), or the flow around a windturbine.
Original language  English 

Qualification  Doctor 
Awarding Institution 

Supervisors/Advisors 

Award date  2005 Apr 14 
Publisher  
ISBN (Print)  9162864432 
Publication status  Published  2005 
Bibliographical note
Defence detailsDate: 20050414
Time: 13:15
Place: Room M:E, Mbuilding, Ole Römers väg 1, Lund Institute of Technology
External reviewer(s)
Name: Sorensen, Jens N.
Title: Professor
Affiliation: Technical University of Denmark (DTU)

Subject classification (UKÄ)
 Fluid Mechanics and Acoustics
Keywords
 Mechanical engineering
 hydraulics
 plasma
 Technological sciences
 Teknik
 fluiddynamik
 plasmas
 Gaser
 fluid dynamics
 Gases
 Inhomogeneous Wave Equation
 Acoustic Boundary Conditions
 Acoustic Source Terms
 LES
 Computational Aeroacoustics
 Turbulent Flows
 vacuum technology
 vibration and acoustic engineering
 Maskinteknik
 hydraulik
 vakuumteknik
 vibrationer
 akustik