The Study On The Main Noise Source Of Underwater Elastic Structure Based On Near-field Beamforming

Near-field beamforming is an effective method for noise source identification. First, the traditional beamforming arithmetic is introduced in the paper, and then one-dimension beamforming method in the near field condition is derived, which is an extended two-dimension condition. Three different algorithms including delay-and-sum arithmetic, cross-spectral arithmetic and cross-spectral arithmetic with autospectra exclusion are introduced and compared numerically, and the result show that the auto-spectrum removal method is the most effective one in the three methods.As the hydrophone array layout plays an important role in the output of beamforming, the effect of the main parameters and characters of the hydrophone array on noise source identification are also discussed in this paper. The theoretical description and numerical realization show that a well designed array should have higher resolution, lower maximum sidelobe level and smaller mainlobe width. The emulation experiments of various array styles with various source models have been carried out and the results are very good.Finally, the accuracy and feasibility of the three beamforming measurement technique are validated by experiments.