Research On Several Key Problems Of The Acoustic Radiation And The Acoustic Sensitivity Analysis Based On The Wave Superposition Approach

The noise control engineering and the vibro-acoustic optimization design are becoming more and more important at present. In this dissertation, the methods for the computation of acoustic radiation and acoustic sensitivity analysis are presented. After a brief presentation of the state of the art of the acoustic radiation and acoustic sensitivity methods, several new methods are proposed. Firstly, the wave superposition approach (WSA) based acoustic sensitivity formulations are given for both free field and semi-free sound field circumstance. Secondly, a statistic wave superposition approach (SWSA) based on the conventional wave superposition approachis presented. It can be used to calculate the acoustic quantities of the acoustic field caused by the vibrating structure subjected to random excitations. And also the acoustic sensitivity analysis based on the SWSA is developed. Finally, in order to increase the computational efficiency in high frequency band, an energy source wave superposition approach (ESWSA) is proposed. Both acoustic radation and acoustic sensitivity analysis based on the ESWSA are developed. The main contents in the dissertation are summarized as follows:In chapter One, the history and the state of the art of the acoustic radiation, acoustic sensitivity and the numerical computational methods have been reviewed. And then the problems of the above methods and corresponding methods to conquer those problems are presented. Finally, the research topics in the dissertation are determined based on the literature review.In chapter Two, after a short introduction of the acoustic theory, the boundary Helmholtz integrating equation and the boundary element methods are reviewed. Based on the boundary element methods, the theory of acoustic sensitivity analysis with respected to the structure design parameters and numerical methods of the acoustic sensitivity analysis have been given and discussed.In chapter Three, the wave superposition approach to compute acoustic radiation is proposed. After a simple review of this method, the comparison between the boundary element method and the wave superposition approach is studied. Then the numerical implementing process and relative factors that may affect the precision of the results of WSA have been given. The correctness and validity of the wave superposition approach used in the acoustic radiation analysis and acoustic sensitivity analysis are validated by the simulation and experiment results.In chapter Four, the semi-free field wave superposition method for the acoustic radiation is introduced. Its correctness is validated by the simulation and the experiment respectively. Subsequently, the acoustic sensitivity analysis formulation under the semi-free field circumstance is presented. Its correctness and feasibility are verified by the numerical simulations. At the end, the reflected sound wave and the other factors that may have certain effect on the semi-free field acoustic analysis are discussed.In chapter Five, the statistical wave superposition approach for the random acoustic field which generated from the vibrating structure subjected to the stochastic excitation are proposed. The statistical wave superposition approach combines the conventional wave superposition approach and the statistical method. It is tested by the results of the experiment. Then the formulations of the acoustic sensitivity analysis based on the SWSA are also presented. The numerical simulation verified the validity of the proposed acoustic sensitivity analysis method.In chapter Six, the energy source wave superposition approach for the acoustic computation at high frequency band is presented. And the acoustic sensitivity with respected to the structure design parameter based on the ESWSA has been studied. The correctness is investigated by the numerical simulations.In chapter Seven, the researches in this dissertation are summarized, and some topics for further study are given.