摘要:
海底对浅海声传播的影响很大。海底有复杂的多层结构。在计算声场时如果把多层海底的影响都考虑进去,就会使计算复杂化,得不出一个清晰的物理图象。因此,在计算中往往使用海底反射损失系数来代替多层海底的模型。但海底反射损失与角度有复杂的依赖关系。为了计算方便,提出过不少简化模型。已经使用的模型有反射损失与角度无关、与角度一次方成正比;后来又提出反射损失在某一临界角之下与角度一次方成正比,在临界角之上与角度无关的三参数模型,克服了远场与近场衔接的问题[1,2]。但这些模型不一定在所有情况下都能反映海底反射损失与角度的关系的主要特征。本文提出一个近似方法,可以计算海底反射损失按任意规律随角度单调上升的情况下的声场。
Abstract:
An approximate method is suggested to calculate the transmission loss of sound field in homogeneous shallow water with sea bottom,the reflection loss of which is arbitrary monotonely increasing function of angle.The shallow water layer is considered as angular filter with beamwidth,varying with distance.An "equivilent rectangular filter" method is suggested and a simple relation between angular function of bottom-reflection-loss and range dependence of transmission loss of sound field is found.For the case of approximation in linear segments,the "transition ranges" of sound field correspond to the turning points of bottom-reflection-loss curve.The angular dependence of bottom-reflection-loss can be easily calculated from the transmission loss data.Results are compared with "three-parameter-model" as a special case.
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