Radiated Noise Measurement Of Underwater Low Noise Level Target Based On Nested Biconical Array

The research on the measurement method of radiated noise from ships and underwater vehicles can provide support for the analysis of acoustic field characteristics,acoustic concealment performance evaluation and acoustic performance optimization design of underwater target radiated noise.With the development of vibration and noise reduction technology,the radiated noise of quiet submarines is more and more close to the ocean background noise.As a result,the requirement of array performance for radiated noise measurement is increasing,and the existing noise measurement system is more and more difficult to meet the measurement requirements of new submarines.Aiming at the problem of radiated noise measurement of underwater low noise target,this paper studies the influence of ocean waveguide,the characteristics of structural noise source and the performance optimization of receiving array,and establishes the radiated noise measurement model and method of structural noise source based on nested biconical array.Based on the influence of ocean wave guide,the influence of nonuniformity of sound energy distribution on noise measurement in ocean environment is studied.Based on the theory of ray acoustics,the similarities and differences of sound wave propagation laws in shallow water and free field are compared.By using bellhop software,the influence of parameters such as sound source frequency,waveguide depth and sound source depth on sound energy distribution is analyzed,and then the influence of non-uniformity of sound energy distribution on the measurement results of radiated noise from point source target is discussed.Further break the previous research on the point source assumption of underwater target,analyze the underwater sound field characteristics of complex structure noise source in detail,lay the foundation for determining the radiated noise measurement system and method for the radiated sound field of structure noise source.The formulas of equivalent source method for free field and shallow water waveguide are derived.Based on the equivalent source method,the sound field radiated by structural noise source in free field and shallow water environment is predicted by processing the waveguide Green’s function,and the prediction results are compared with the COMSOL calculation results,which provides support for the analysis of sound field radiated by structural noise source and the acquisition of array receiving data Hold on.The performance of the receiving array is optimized,and the optimized form of the volume array nested biconical array,which can obtain the constant beamwidth receiving ability in both horizontal and vertical directions,is established.The construction principle of biconical array is described,and the influence of array parameters such as twist angle,maximum radius,number of layers and columns on its performance is analyzed;the processing method of constant beamwidth array based on nested biconical array is studied,and the spatial gain performance of nested biconical array is analyzed;the noise measurement performance of nested biconical array and nested linear array in free field and shallow water is further analyzed,and the results are verified Compared with the current array,the bright nested biconical array has obvious performance improvement.Considering the influence of ocean waveguide,the characteristics of structural noise source and the performance of receiving array,the measurement model and method of radiated noise of structural noise source based on nested biconical array are established,and the conditions that should be met in noise measurement of structural noise source are comprehensively analyzed;the influence of different environment and measurement parameters on the measurement results of nested biconical array is compared and analyzed,and the influence of nested biconical array on structural noise source is proved,the feasibility of noise measurement and the superiority of array performance are discussed.