浅水近距离测量声场的干涉结构分析

为指导浅水中水平距离在十倍水深范围内进行的近距离声学测量工作,选取对软底浅水声场产生主要贡献的直达声线和一次水面反射声线,经过合理的近似处理,以射线解析方式给出了中低频信号声场干涉结构的表达式,并将表达式由单频信号推广到宽带信号和线性调频等信号形式。所得到的解析关系式定量给出了浅水中声场干涉结构与信号频率、信号带宽、设备布放深度和水平距离等参数的关系,由此进一步得到浅水条件下中近距离干涉声场的一些特性和规律。通过数值模拟和实际试验数据对上述关系式所进行的检验表明:在浅水的常规测量试验条件下,这些关系式可以较为准确地反映近距离干涉声场的起伏特征,由关系式推论得到的声场特性和规律也得到了初步验证。 

Analytical study on acoustic interference pattern in shallow water

Analytic formulas on acoustic interference patterns are derived by ray method to guide acoustic measurements in shallow water,especially those with horizontal distances less than ten times of water depth.We take some reasonable and necessary approximations and neglect those less important rays for a more concise expression.Monofrequent signals,complicated signals and frequency-modulated signals are all studied.The analytic formulas represent the quantitative relationships between the interference-pattern and the signal frequency,bandwidth,depth of source and horizontal distance.Several inferences are also deduced from the formulas.Both numerical simulations and experiment data are presented to prove that these formulas and their inferences can describe the critical characters of the acoustic interference pattern in waveguide with satisfying precision.