| With the rise in global temperature,the trend of melting Arctic glaciers has intensified,which has laid the foundation for the development of the Arctic;the continuous progress of science and technology has accelerated the speed of Arctic development.my country attaches great importance to its rights and interests in the Arctic,marked by the proposal of the "Ice Silk Road" strategy,the general direction of my country’s scientific research in the polar regions has been established.The floe(i.e.floating ice sheet)is a natural refuge for targets under the ice.In order to determine the location of targets under ice,it is necessary to develop cross ice positioning technology.Acoustic method is the main means of underwater target location;The geometric structure of the ice sheet makes the guided wave become the key point of the cross ice positioning technology.Based on the research background of polar acoustic target location,this paper proposes a numerical modeling and simulation study of cross-ice acoustic detection and location technology.For the purpose of passive positioning of underwater targets across ice layers,the current research faces the following difficulties:1.At the fluid-structure interface,the mechanism of acoustic wave propagation and evolution is still unclear.2.The changing ice cross section has an important influence on the propagation of ice guided waves.3.The conditions for verification using field tests are limited.In view of the above difficulties,based on the existing underwater acoustic theory,ultrasonic theory in solids,ultrasonic theory in solids,and the finite element simulation platform,the scientificity and feasibility of the cross-ice positioning method are studied.By establishing a fluid-structure coupling simulation model excited by underwater sound sources and received on ice,the purpose is to reveal the propagation law of sound waves in different media and the evolution mechanism on the coupling surface.The analysis method is used to discuss the time-frequency characteristics and polarization characteristics of various types of arriving waves differently,and further summarize the propagation law of ice-layer waveguides.By scientifically designing the field test plan to obtain the measured data,combined with the simulation experimental data,the predicted positioning plan is verified,and experience and assistance are provided for other related projects of polar acoustic detection in the follow-up.The results obtained in this paper are as follows:1.Using simulation software,an ice-water coupling model in two-dimensional space is constructed to study the process of sound waves propagating from underwater to ice.During the research,it was found that the guided waves in the ice layer exhibited multi-modal characteristics.Therefore,a set of methods for judging the guided wave modes based on phase velocity and instantaneous frequency were established,and the rationality of the method was preliminarily verified.2.Based on the results of the above analysis and judgment,combined with the theory of ice-layer acoustic waveguides,a method of trans-ice positioning based on guided waves is carried out,and the positioning results are analyzed and discussed.3.Combined with the field test data,the ice target positioning is carried out,and the data obtained from the field test and the simulation test data are compared,and the results achieve a high degree of agreement. |
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