Research On Near-field Acoustic Focusing Technology Of Array

There are different kinds of mechanical noise inside the submarine. It is a very complex system with multi-source noise. If the location of the main noise source can’t be confirmed, it will be difficult to effectively reduce the source level. It is important for reducing radiated noise of submarine and improving the acoustic covertness. The traditional measurement method of far field sound source locating has some limitations, so it is particularly important to do some research on the high resolution work in near field. The paper studies the acoustic focusing problem in the near field area, aiming to determine the position of submarine main noise sources and corresponding energy contribution and locate the sound source and the energy distribution. It will provide theoretical guidance for vibration reduction and acoustic fault diagnosis.Firstly, the paper introduces the basic theory of near field acoustic focusing and analyzes the discriminative criterion between the near field and far field, depicts the near-field narrow-band signal model, broadband signal model and the coherent source model respectively. Deduce the receiving signal model of uniform line array and cross array and analyze the parameters which influent the effect of sound source estimation.Secondly, the paper conducts some analysis and simulation on narrowband and broadband signals of near field acoustic focusing. Giving the sound focusing algorithm which is based on joint amplitude - phase compensation. The algorithm is used to estimate the sound source location and energy. Analyze the performance of the different array of near field acoustic focusing algorithm by the simulation. General class of high resolution subspace methods can not solve the problem of coherent source, and the parameter estimation algorithm has large amount of calculation. In order to solve this situation,this paper gives a kind of singular value decomposition algorithm which is based on phase matching principle (SVDSPM),the method does not need to use the data covariance matrix,and get some unique advantages to solve the small angles coherent sources.Finally, analyzing the data from anechoic tank for the underwater targets’ noise sources near-filed location methods. The experiment results and theoretical analysis is consistent,it proves the availability of these methods which are studied. Design "near-field noise source location analysis" software with MATLAB and VC++ mixed programming. This program is divided into two parts. One is simulation analysis and the other is experimental data processing. The program can give some advice on the choice of parameters, formation provide the some references and progress the experiment data.