Print Email Facebook Twitter Modelling and development of a resonator-based noise mitigation system Title Modelling and development of a resonator-based noise mitigation system Author Peng, Yaxi (TU Delft Mechanical, Maritime and Materials Engineering) Contributor Tsouvalas, A. (mentor) Metrikine, A. (graduation committee) Belderbos, Edward (graduation committee) van Dalen, K.N. (graduation committee) Degree granting institution Delft University of Technology Programme Offshore and Dredging Engineering Date 2017-10-17 Abstract Anthropogenic underwater noise generated by pile driving has been an issue of serious concernfor a long period of time. The underwater noise pollution from pile driving could pose a threatto marine mammals. To reduce the low-frequency noise, many offshore companies developvarious treatments and alternatives for pile driving. In this study, the focus is placed on aresonator-based noise mitigation technique.The first part of the thesis focuses on the investigation of the existing resonator-based noisemitigation systems. A mathematical expression for the resonance frequency of an individualopen-ended resonator is derived. To validate this expression, a finite element model is built inCOMSOL. To compare the acoustic performance with the HSD, a finite element model is alsobuilt for the HSD mitigation system. To describe the acoustic performance of the resonatorsfor generic use, the frequency response function of an open-ended resonator is analyticallyderived based on the assumption that the resonator behaves as a linear SDoF system. Thederivation of the parameters of the equivalent SDoF system representing each individualresonator is based on appropriate fitting of numerical results obtained in COMSOL.The second part of the thesis deals with the development of a new design of a resonator systemnamed Qiu. To install the resonator system in a more flexible way, the air is encapsulated inthe resonator. A finite element model is also developed in COMSOL for the Qiu resonator.In the last part of the thesis, a three-dimensional vibroacoustic model is developed in orderto find the optimal properties of the underwater resonator and to improve the existing noisemitigation techniques. The model requires the proper description of the noise source, theresonator and the acoustic waveguide. The normal mode method is used to compose theGreen’s function of the waveguide. The boundary element method is then employed in orderto obtain the total pressure field. The frequency response functions derived in the first partof the thesis are subsequently used to describe the acoustic behaviour of the resonators. Aparametric study is presented in order to define the principal factors for effective noise mitigation.In addition, the several cases are investigated in order to obtain the optimal propertiesof the resonator and the optimum configuration of the array of resonators surrounding thesound source to maximise noise reduction. Subject underwater acoustic modellingresonatornoise mitigation systempile-driving To reference this document use: http://resolver.tudelft.nl/uuid:409c8058-190b-4835-811f-35c376d94ccb Embargo date 2022-10-28 Part of collection Student theses Document type master thesis Rights © 2017 Yaxi Peng Files PDF Yaxi_Peng_Thesis_Report.pdf 24.73 MB Close viewer /islandora/object/uuid:409c8058-190b-4835-811f-35c376d94ccb/datastream/OBJ/view