Anti-active Detection Underwater Target Acoustic Stealth Shape Optimization Design

At present,sonar equipment and detection mode are undergoing profound changes.the integration of active/passive,multi-frequency and multi-function and multi-base cooperative detection will be the future development direction of sonar technology.As a result,the target strength(TS)control technology of anti-active detection will become a hot topic in the field of underwater acoustic research gradually.As the main equipment of TS control,muffler coating has been applied in engineering.After several generations of development,it is still difficult to meet the design requirements of low-frequency acoustic stealth,so it is urgent to develop a new method to effectively reduce the acoustic scattering of underwater targets.Aiming at the largest contribution to the echo of the mirror reflection echo,by studying the target shape with monostatic target strength or the echo strength of inner link,combined with the optimization algorithm and the target scattering numerical calculation method,this project creating attempt to establish underwater acoustic stealth shape optimization methods against active sonar detecting,so as to reduce and control the TS and angle detection rate of engineering underwater target within the detection angle range and detection frequency band.To intuitively understand the influence of the target surface shape on the acoustic scattering echo,this topic firstly calculates and analyzes four typical simple shape targets(ellipsoid,truncated cone,cylinder and elliptic cylinder),the deformation of different shape parameters and three types of the simplified model of submarine(Benchmark submarine,Be TSSi II submarine and Los Angeles nuclear submarine)TS azimuth-frequency characteristics,by comparing its shape parameters,the preliminary influence laws of target shape on acoustic scattering are appeared.On this basis,in view of the free field goals such as UUV/Torpedo head,submarine in the acoustic stealth shape optimization problem,combinating optimization algorithm,target shape mathematical description and the underwater acoustic scattering numerical calculation method,target stealth shape optimization methods are developed based on Finite Element Method(FEM)dimension reduction techniques and Plate Element Method(PEM).This method can realize the free field target acoustic stealth shape optimization design within given frequency bands and acoustic incident angles.In view of the non-axisymmetric complex submarine target,the submarine can be simplified into hull and enclosure using component phase interference superposition method in target acoustic stealth shape optimization method based on PEM.Within the help of COMSOL with MATLAB coupling module,it is successful in complex submarine acoustic stealth shape design using established the optimization method based on PEM.The optimization design of submarine appearance is smooth,which has a lower TS and angle detection rate within most of the detection angles and frequency bands.It can fully show the advantages of the proposed optimization method.Aiming at the acoustic stealth contour optimization problem of targets near the seabed interface such as Manta mine,this project fully considers the characteristics of the fusion between the target and the real Marine environment.The application of the optimization method is extended to the acoustic scattering optimization problem superimposed by multiple propagation paths based on PEM.In this paper,the classical PEM is modified to consider the contribution of shadow region on bistatic acoustic scattering calculation,which the integral area is also modified.Furthermore,the COMSOL coupling MATLAB module is used as the platform to combine the target shape,the automatic subdivision of 3D grid with the modified PEM.Then,the optimization method for the acoustic stealth shape of the bottom target is developed successfully using the GA optimization algorithm as the control method.This method can realize the auto-optimization design of the acoustic stealth shape of Manta mine at given frequency bands and given grazing angle ranges under the real seabed.Finally,by carrying out the acoustic scattering lake experiment of the Benchmark submarine scaling model,the accuracy of calculating the scattering sound field of the nonaxisymmetric object by the PEM is partially verified in this paper,which indirectly guarantees the effectiveness and accuracy of the acoustic stealth shape optimization method for the submarine hull and enclosure in the free field.The research results obtained in this subject will have certain guiding significance and reference value for the acoustic stealth shape design of submarine,UUV/Torpedo,Manta mine and other underwater targets.