Research On Vector Field Characteristics Of Deep-sea Ambient Noise

In recent years,with the establishment of the goal of maritime power,Marine project research has become a domestic development demand,and the role of underwater acoustic technology is becoming increasingly important.And Marine environmental noise is one of the background interference that affect sonar equipment performance,at the same time due to the Marine environment noise field with a lot of information about the Marine environment,so the study of ocean ambient noise field,meaning is not limited to the interference of underwater acoustic equipment,more can make use of relevant characteristics of the noise field inversion can’t direct measurement of hydrology,meteorology and other information.The Marine environmental noise has been studied extensively,including its level,directivity and correlative characteristics.Considering that the seabed topography will change with the change of horizontal distance under actual conditions,this paper will establish a parabola-ray three-dimensional noise field model based on the theory of parabolic equation and ray acoustics to explore the vertical spatial characteristics of the deep-sea environmental noise field,including vertical correlation characteristics and vertical coherence characteristics.Compared with the K/I fast field model and the K/I normal wave model,the results show that the proposed model is feasible.In addition,the expression of spatial characteristics at any two points in the space of noise field is given.Secondly,considering the large-scale application of vector hydrophone,this paper also extends the parabolic noise model to the vector field,establishes a three-dimensional parabolic vector noise model,and explores the vector characteristics of the deep sea environmental noise field.Compared with the experimental data of the South China Sea,the results show that the model is feasible to some extent.Model based on the above,this thesis analysis the shallow water and deep waters,the waveguide environment noise field vertical space characteristics,the results showed that the uniform velocity of sound environment,receiving array in depth location of the noise field has little effect on vertical correlation properties and vertical directivity,the sound velocity profile in the deep sea environment,the depth of the receiving array position vertically related to noise field and vertical directivity effect more apparent,different water depth and distance on the bottom of the ocean environment also vertically related to noise field and vertical directivity has obvious effect.Finally,the three-dimensional parabolic vector noise model is used to give the expression of vertical spatial correlation coefficient,the expression of horizontal acoustic energy flow and the calculation format of azimuth Angle estimation.The vertical spatial correlation characteristics of low-frequency vector noise field are simulated,and the directivity of horizontal acoustic energy flow of low-frequency non-uniform noise field is explored.The simulation results show that the vertical correlation of vector noise field and the estimation of azimuth Angle are affected by different water depth and the depth position of vector hydrophone,and the change of water depth has more influence,while the noise source intensity has little influence on the estimation of azimuth Angle.