Research On Near-field Acoustic Holography Method Based On Statistical Optimal And Equivalent Source Method

With the development of science and technology,people are paying more and more attention to noise quality.While people enjoy the convenience brought by mechanical products,they are also suffering from the health hazards brought by noise.Therefore,it is necessary to control the noise of mechanical and electrical products.The accurate identification of noise sources is the prerequisite for noise control and sound quality design of electromechanical products.Traditional noise source identification methods have low accuracy and cannot accurately identify noise sources.With the continuous deepening of holographic technology research,Williams et al.established the basic theory of Nearfield Acoustic Holography(NAH)technology at the end of the 20th century.However,this technology still has some difficulties in actual engineering.In this paper,three implementation algorithms of near-field acoustic holography technology are studied,in order to improve the current difficulties of the three algorithms,and to improve their reconstruction accuracy.First,in NAH based on the spatial Foureir transform,the evanescent wave in the high wavenumber domain is submerged by noise,which causes the reconstruction process error to be magnified and even the reconstruction result to be invalid.This article discusses the importance of filtering and conducts simulations.verification.The selection of parameters and the causes of errors are analyzed,and a reasonable selection range of reconstruction parameters is given.Second,the statistically optimal near-field acoustic holography is discussed separately in planar and cylindrical coordinate systems.When the traditional statistical optimal algorithm is discrete in the wavenumber domain,it is generally selected at equal intervals.This article introduces a method to achieve sound field reconstruction by selecting wavenumber vectors at unequal intervals in conjunction with L-curve to reduce the error caused by evanescent waves in the reconstruction process,and introduce this method to the cylinder statistical optimization In near-field acoustic holography,simulations have verified the effectiveness of this method for holographic reconstruction of sound source structures with different shapes.Third,based on the NAH of the equivalent source method,to solve the ill-posed problem of the source intensity density in the reconstruction process,the regularization parameter selection method is studied.In view of the difficulties in the practical application of the equivalent source method and the statistically optimal NAH,a joint algorithm combining the equivalent source method and the statistical optimal is proposed,which solves the problem that SONAH cannot be applied to non-universal planes and practical applications There is a problem of difficulty in measurement.And compared with the traditional equivalent source method,it is verified through simulation that the joint algorithm has a good effect on improving the measurement aperture size limit.