近海环境下的声传播特性研究

发布时间：2018-07-28 20:39

【摘要】：近海声学环境复杂多变，由于其水深往往较浅，温度受光照、风浪等因素影响明显，，岸基噪声丰富、水面船只来往密集，潮汐现象对水位改变较大，这些现象都使得近海声传播的研究经久不衰。非线性内波经常在近海环境中被捕捉到，关于内波引起声场起伏的规律研究在过去的30年理论和实验都取得了进展，对于浅海非线性内波引起的声场起伏的定性描述基本成熟。然而，由于浅海非线性内波描述本身的不完善和浅海声场的影响因素较多，浅海非线性内波引起声场起伏的定量规律描述还需进一步研究，本文针对一些新的实验数据采用一些新的方法和思路进行了研究。在声传播研究中，射线和简正波理论是应用最为广泛的理论，关于两种理论之间联系的研究也是声学研究的重要内容之一。波导不变量可有效地用于描述水下声传播特性，通常采用简正波理论描述和定义。本文在理论部分中针对海洋环境与距离无关或者存在轻微扰动时的声传播，利用简正波水平干涉结构距离上的周期性与射线水平跨距相等的特点，采用简洁方式证明了射线稳定性参数与简正波波导不变量相等，在射线和简正波理论中建立了一个新的联系，并通过简正波干涉声场数值模拟，对简正波的相长干涉形成能量包沿着射线路径传播进行了验证，说明了简正波和射线理论的共通性。文章结合远距离射线模型声传播仿真结果，对射线稳定性参数及射线传播时间稳定性之间的关系进行了分析和讨论。仿真结果表明，射线稳定性参数作为射线理论中一个新的参数，能够反映海洋环境变化，可用于描述声传播特性。本文针对2013年朝连岛附近海域实验所得的温度和声传播数据进行分析，研究温度数据和声传播数据的统计特性，结合实验数据进行理论验证。根据实测数据构建温度场模型，在全时段内对声传播过程进行还原并进行简正波过滤，对发现的声传播规律加以总结。针对实验实测数据，给出了射线稳定性参数曲线和伪彩图，并对照简正波过滤结果进行了分析。结果表明，实验中内波的存在使部分简正波系数（归一化）改变0.1左右。射线稳定性参数（绝对值）主要集中在0-3之间，内波出现时可以达到5或者更大。文章中分析的与简正波对应的射线稳定性参数与简正波系数在遇到内波时其起伏变化规律吻合。分析表明射线稳定性参数的变化与海洋环境密切相关其可以作为一个全新的量可以表征浅海环境变化。
[Abstract]:The offshore acoustic environment is complex and changeable, because its water depth is often shallow, the temperature is obviously influenced by light, wind and wave, the shore noise is abundant, the water surface ships are dense, and the tidal phenomenon changes the water level greatly. All these phenomena have made the study of offshore acoustic propagation enduring. Nonlinear internal waves are often captured in offshore environments. In the past 30 years, both theoretical and experimental studies on the regularity of acoustic field fluctuations caused by internal waves have made progress, and the qualitative description of acoustic field fluctuations caused by nonlinear internal waves in shallow water is basically mature. However, due to the imperfection of nonlinear internal wave description in shallow water and the influence of many factors on the sound field in shallow water, the quantitative description of the fluctuation of sound field caused by nonlinear internal wave in shallow water needs to be further studied. In this paper, some new methods and ideas are used to study some new experimental data. In the study of acoustic propagation, the theory of ray and normal wave is the most widely used theory, and the study on the relationship between the two theories is also one of the important contents of acoustic research. Waveguide invariants can be used to describe underwater acoustic propagation effectively. In the theoretical part, in view of the sound propagation in the marine environment which is independent of distance or slightly disturbed, the periodicity of the structure distance of normal wave horizontal interference is equal to the horizontal span of ray. It is proved that the parameter of ray stability is equal to that of normal wave waveguide in a simple way. A new relation is established in the theory of ray and normal wave, and the numerical simulation of sound field of normal wave interference is carried out. In this paper, the phase length interference of normal wave is verified and the energy packet propagating along the ray path is verified, which shows the commonality between the normal wave and the ray theory. In this paper, the relationship between the parameters of ray stability and the time stability of ray propagation is analyzed and discussed based on the simulation results of sound propagation in long distance ray models. The simulation results show that, as a new parameter in ray theory, the ray stability parameter can reflect the changes of marine environment and can be used to describe the acoustic propagation characteristics. In this paper, the temperature and sound propagation data of the sea area near Chaolian Island in 2013 are analyzed, the statistical characteristics of the temperature data and sound propagation data are studied, and the theoretical verification is carried out with the experimental data. Based on the measured data, the temperature field model is constructed, the sound propagation process is reduced and the normal wave filter is carried out during the whole period of time, and the discovered sound propagation law is summarized. Based on the experimental measured data, the ray stability parameter curve and pseudo-color map are given, and compared with the results of normal wave filtering, the results are analyzed. The results show that the partial normal wave coefficient (normalized) is changed by 0.1 or so due to the existence of internal waves in the experiment. The ray stability parameters (absolute values) are mainly between 0 and 3, and the internal waves can reach 5 or more when they occur. The ray stability parameters corresponding to the normal wave are consistent with the fluctuation of the normal wave coefficient when the internal wave is encountered in this paper. The analysis shows that the variation of ray stability parameters is closely related to the marine environment which can be used as a new quantity to characterize the variation of the shallow sea environment.
【学位授予单位】：中国海洋大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P733.2

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