Research On The Source Identification Of Moving Target In Semi-space Based On Acoustic Holography

Traditional measurement is difficult to determine the location of noise sources, which associated with underwater moving vehicle. Near-field acoustic holography is a very effective technique for noise source identification, location and sound field visualization. Based on boundary element method, the acoustic holography method has been established which can be applied to field reconstruction of the arbitrary shaped moving structure. It is very valuable in engineering.First, the theoretical verification of BEM-based NAH has been done, which applied to the reconstruction of the arbitrary shaped moving structure. Secondly, the sensitivity of the reconstruction results to measurement error has been analyzed. Simulation indicates: truncated singular value filtering method and Tikhonov regularization can stabilize the reconstruction process and inhibit measurement error. On this basis, the influence of various parameters to holographic results was discussed. Then the principle of MFAH is presented. When the target is moving, the hydrophone receives the time-domain signal with Doppler Effect. MFAH can change it into holographic sound pressure signal in space. Thus, a dual-plane holographic data required in BEM-based NAH can be obtained by two stationary linear arrays. In addition, through the theoretical analysis of the velocity, velocity measurement error and other parameters, a phase-corrected formula is given. Simulation indicates: when the Mach number is less than 0.1, the algorithm error is very small, and can be ignored. The sound reconstruction error will increase with the speed measurement error's rise.For the actual working conditions, the formula of acoustic holography of the moving structure in a semi-free space is presented. A simulation is done, in which a hooded cylindrical shell is used as the research object. The validity of the proposed method is verified by numerical simulating.Finally, in the semi-anechoic tank, an experiment was studied. The algorithm proposed in this paper was used in the experiment to reconstruct the acoustic field of a hooded cylindrical shell, and the satisfactory results were obtained. It further proved the feasibility and superiority of the method.