Research On Sound Field Reconstruction Method Of Underwater Structure Noise Sources

Testing and analysis of noise sources is an important research content in the field of vibration and noise reduction.Finding the location of the main noise source in the mechanical vibration system and determining the spatial distribution can provide a basis for the implementation of vibration and noise reduction measures.It will further enhance the submarine’s acoustic stealth performance and ensure its hidden combat capabilities.In order to solve the problems of complex internal mechanical structure,serious coupling of spatial distribution and strong coherence among sound sources,the reconstruction method of underwater structure noise source sound field is an effective analysis method and the leading condition for the implementation of vibration reduction and noise reduction measures.Therefore,it is of great significance to analyze the applicability of the reconstruction method for practical engineering application.This paper starts with the analysis of the radiation field characteristics of underwater structure noise sources,and comprehensively analyzes the application of Boundary Element Method,Wave Superposition Method,Kirchhoff approximation method and Element Radiation Superposition Method.The relationship between the vibration of the structure surface and the sound field is established.In this paper,the vector acoustic field model of a typical underwater structure(a finite length simply supported cylindrical shell)is constructed based on the element radiation superposition method,and the accuracy of the model is verified.Then,based on the acoustic radiation characteristics of underwater structural noise sources,the near-field acoustic holography method can reconstruct the sound field at low frequency,but the reconstruction effect is poor at medium and high frequency.The focused beamforming method can realize the equivalent sound source distribution of noise sources at medium and high frequencies,while generating spatial aliasing at low frequencies.Therefore,the holography-focusing method used to reconstruct the sound field in the whole frequency band.In this paper,the reconstruction method of holography-focusing integrated sound field is further studied.Based on the vector sound field modal which constructed by the Element Radiation Superposition Method,we use the data of complex sound pressure and particle vibration velocity to reconstruct the surface vibration velocity of structure sound source.Through theoretical derivation and simulation,the error sensitivity of the two cases is analyze.The results show that the reconstruction process based on complex particle velocity is more stable.We use Thikhonov regularization method to stabilize the reconstruction process,and explore the calculation method of optimal regularization parameters.We analyze the parameter conditions that affect the reconstruction performance,and determine the optimal parameter range.We use the focused beamforming technology to reconstruct the structure sound field excited by single frequency or broadband frequency.We analyze the radiation characteristics of structural sound source,and then select the appropriate focal plane to reconstruct the equivalent sound source.The results show that the high-resolution algorithm has higher requirements for the matching degree of the guidance vector,while the conventional beamforming has better tolerance.In the case of incomplete matching of the guidance vector,the acoustic field reconstruction process can be realized.Finally,the applicability and effectiveness of holographic method in low frequency and focused beam forming method in medium and high frequency are analyzed by analyzing the experimental data of real boat cabin model.It provides the experimental data analysis results support for the practical engineering application of the method.