Development and validation of underwater radiated noise analysis method using computational fluid dynamics simulations
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School of Engineering |
Master's thesis
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Date
2024-09-30
Department
Major/Subject
Marine Technology
Mcode
Degree programme
Master's programme in Mechanical Engineering
Language
en
Pages
94
Series
Abstract
The large amount of marine freight and passenger traffic is inevitably responsible to various types of pollution of the areas in which ships operate. Among these types of pollution there is Underwater Radiated Noise which represents a danger to various species of marine animals. To mitigate such pollution it is necessary to design quieter vessels by understanding the phenomenon and being able to predict the emitted noise during the design stage. In this thesis a method for predicting the noise emitted by cavitating flows using Computational Fluid Dynamics simulations has been developed. To do so, an extensive collection of cavitation and hydroacoustics theory has been performed to reason out the physical background of the method. The development process has been initiated in a two-dimensional hydrofoil case and then transferred to a three-dimensional hydrofoil case that has been used for the improvement and validation of the method. Finally, the model has been applied to simulate a propeller in a cavitation tunnel to test its applicability to industry-like cases. The developed method is based on the Detached Eddy Simulation model for predicting turbulence, the Schnerr-Sauer model for predicting cavitation, and the Ffowcs Williams-Hawkings acoustic analogy for predicting sound production and radiation. The method has been proven to be sufficiently accurate to give an acceptable indication of the amount of noise produced by a cavitating flow. Some discrepancies with reference and experimental values have been observed. The origin of this discrepancies is mainly found in the incompressible flow assumption and in the inherent limitations in both the meshing techniques and the models used.Description
Supervisor
Vuorinen, VilleThesis advisor
Tanttari, JuhaKeywords
fluid dynamics, CFD, hydroacoustics, cavitation, acoustic analogy, propeller