Fluid-Structure Interaction Effect To The Structure-borne Noise Propagation

• Main Author: 劉嘉洪
• Other Authors: Wei-Hui Wang
• Format: Others
• Language: zh-TW
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/50668931766221467779

碩士 === 國立海洋大學 === 系統工程暨造船學系 === 88 === A couple FEM/BEM for solving fluid-structure interaction problem in structure-borne noise propagation and underwater acoustic radiation is present in this paper. The finite element method is extensively used to analyze a complicated structure, while the boundary element method is ideally suited to handle the ambient fluid field problems. Both numerical methods discretize separate domain, i.e., FEM for discretization of the structure domain and BEM for discretization on the wetted surface governed by Helmholtz integral equation in the infinite fluid domain. In order to improve the habitability and stealth onboard a ship low noise condition is required in various types of ships. One of the dominant components is the radiated airborne and underwater noise caused by ship hull vibration. Accordingly, the estimation of structure-borne sound characteristies of a ship is important in the design of a quieter ship-structure. The hull vibration response and pressure distribution on the wetted surface of a ship subjected to excitation sources can be analyzed by utilizing the developed method. Further discussions on the evaluation of surface complex power, radiation and reactance power have been conducted. Two examples, a submerged spherical shell subjected to a uniformly harmonic pressure and a engine room structure model subjected to machine excitations, illustrate the applications of the analytical model. The surface pressure, the normal velocity on the wetted surface, the surface complex power, the radiation power, the reactance power, the vibrational displacement and the radiated underwater sound pattern have been computed. The comparison of the results by predicted model and the measurement indicates that the numerical model is creditable. In addition, the effect on underwater acoustic radiation at the elastic mounts for the main propulsion engine is discussed.