A Study On Simulation & Application Of Underwater Sound Channel

With the rapid development of computer techniques, at present simulation research has infiltrated into every technology and become an important method of underwater acoustic engineering research.This thesis points out the core question of the simulation of oceanic surroundings is the simulation of underwater sound propaganda and describes simply the five typical methods of solving the wave equation which are used in underwater sound propaganda simulation, and then established the model of multi-path channel and the Pekeris sound field model. At the primary research of the acoustic characters of VLA(vertical linear array) the upper two models are used.In this thesis, when the mathematical model of multi-path channel is established by using the theory of ray acoustic we regard underwater sound channel as an impulse response function of the network, parameters of sonar and underwater environment are as input and researches are as output. Impulse response function of the network model is determined by parameters of eigen rays. Sort method and searching algorithm of eigen rays are presented, and it can quickly and correctly search all the important eigen rays. In order to overcome the influences of sea surface and sea bottom to sound transmission, acoustic parameters of sea surface is corrected by using the Rayleigh scattering model and acoustic parameters of sea bottom is estimated by using the three-parameters model. This improves the precision of the simulation model.When studying the Pekeris sound field model we found that lateral wave contributes greatly to near distance acoustic field, which is only estimated approximatively in open literature and these have great errors. In this thesis accurate numerical prognosis method for lateral wave field, which is named three-segments-integral, is given, so the near distance acoustic field may be predicted accurately. In this studying, we compared the results of acoustic field prognosis on wave theory, normal model and ray model, and the approximate degree of the later two models is given. Normal mode is fit to forecast far distanceacoustic fields more than ten times of the depth of the sea only, but not near distance. Ray model is fit to forecast high frequence acoustic fields. If kh>100, ray model is accurate adequately. The studies of near distance acoustic field coincide with sea (lake) trials rationally in this research.VLA is often used in low-frequency radiated noise measuring, shallow water acoustic research and objects detecting, hi radiated noise measuring angle spectrum must be calculated so that the objects character can be obtained, this is called Sound Field Revise. In this thesis some elemental studies have done in this issue.