Research On Acoustic Radiation Characteristics And Noise Source Identification Method For Underwater Structures

Since the 20 th century,underwater acoustic technology has been rapidly developed.In order to meet the requirements of modern marine military strategy,the vibration and noise reduction of underwater vehicles has always been a key issue for many scholars in various countries.In the underwater vehicle vibration and noise reduction project,how to accurately identify the noise source that plays a major role in the mechanical noise system and identify the spatial distribution and frequency characteristics of the main noise sources of the aircraft from the frequency and the spatial domain,Quantitatively identify the contribution of each major noise source to the radiated noise of the aircraft,so as to effectively take measures to reduce vibration and noise,and become a key technology developed for a quiet underwater vehicle.In this dissertation,based on the research on the testing and recognition of radiated noise sources in large underwater structures,the acoustic radiation characteristics of underwater typical structures are studied.In view of the limitation of traditional point-source spherical surface wave propagation models to identify noise sources,Study on Noise Source Identification of Vibration Transmission Model Based on Radiation Superposition Method.The details are as follows:Element Radiation Superposition Method(ERSM)is a method to quickly predict the radiation field of large underwater structures.According to the principle of unit radiation superposition,a theoretical study of sound transfer modeling method based on unit radiation superposition method is carried out.The analytical expression of the radiated sound field of a typical structural surface piston is obtained.The acoustic radiation characteristics of excited vibration of typical structures such as underwater rectangular plates and cylindrical shells are studied by using analytic method and elemental radiation superposition method.Modal superposition and shell vibration theory are introduced.The comparison between the rectangular plates in air and water,Cylindrical shell radiation characteristics.The applicable frequency range and accuracy of the unit radiation superposition method are analyzed.The normal vibration velocity and radiated sound pressure on the surface of the excited vibration of rectangular plate and cylindrical shell are calculated by three methods: analytic method,numerical method and unit radiation superposition method.The agreement of the results verifies the correctness of the model of vibration transfer in the unit radiation superposition method.In this paper,the basic principles of generalized inverse beamforming algorithm and the Tikhonov regularization method are described.According to the analytic expression of the radiated sound field of the regular baffle surface piston,the acoustic transfer matrix between the target structure surface acoustic source and the receiving array is established instead of the traditional point source sphere Wave propagation matrix to overcome the limitations of traditional point-source spherical spread acoustic propagation model and to solve the problem of refinement and characterization of acoustic source propagation model with complex structure.Secondly,the generalized inverse beamforming method based on vibration transfer matrix In this paper,the generalized inverse beamforming algorithms of the two different transfer matrices are compared and analyzed,and the effect of different parameters on the performance of the algorithm is explored.Based on the rectangular plate structure,The generalized inverse beamforming and planar near-field acoustic holography are carried out.Finally,the vibration positioning and identification experiment of the air-solid support structure is carried out.The experimental results verify the validity and applicability of the generalized inverse beamforming algorithm based on the vibration transfer matrix,Beamforming noise source test performance.