The Study Of Near Field Focusing Beamforming Technology Based-on Vector Array

Ship radiated noise is one of the important indexes of the ship sound stealth, the improvement of which has brought about a revolution into the ship design. Therefore, examining the main noise sources by ship noise identification technique researches, which are the main studies of this paper, is very important. The studies of this paper are as follows:The theory and methods of near-field focusing beam-forming are described first, the performance of which are analyzed theoretically. Simulations are made about the near-field focusing beam-forming with line arrays and the results show the ambiguity between the port hand and the starboard with pressure arrays. Then the corresponding methods with sound vector arrays are put forward combined with the techniques of sound vector hydrophones and array processing. After that, calculations are made and compared for the effects by near-field focusing with different combinations of vector arrays. The analysis of the comparison points out that vector arrays can effectively eliminate the ambiguity between the port hand and the starboard with pressure arrays. In the end, the near-field focusing beam-forming method for moving sources are put forward combined with the principle of the synthetic aperture, and used in the identification of moving sound sources. And this method is used in the analysis of the source identification of moving sources and simulations are made about the main parameters which have influence on the beam performance. It is showed by the simulation results that enlarging the array aperture can only improve the resolution in the direction parallel to the array while reducing the distance between the source plane and the array can improve the resolution in all directions. In the background of noise perturbation, the sound vector array has better performance than the sound pressure array in not only identification but also localization. The influence to the localization performance brought about by the deviation due to the environment becomes larger with the increase of the deviation and is most sensitive to the deviation in the normal direction of array elements.The last, the field work of source identification of moving sound sources was done using the near-field focusing beamforming of moving sound sources, the results of which were satisfactory. It can be concluded that source identification of underwater moving sound sources by the use of near-field focusing beamforming is practical.