有限长双层加肋圆柱壳体低频回声:近似理论和实验

研究了有限长双层加肋圆柱壳体的低频回声特性,提出了一种近似预报方法并进行了实验验证。该方法将回声分为弹性部分和几何部分,弹性部分用薄壳理论求解的包含中间水层的弹性散射波来近似;几何部分用修正板块元法计算的壳体和肋板构成的类似角反射体的几何回声来近似,将两者按能量叠加得到总回声场。低频回声实验的ka值约在5～10之间,通过实测的频率—角度谱与理论计算结果的比较分析了各种回声的形成机理。最后将实测目标强度与近似理论预报的结果进行了对比,两者在大部分角度吻合良好。

Low-Frequency Echo from Finite Ring-Stiffened Double Cylindrical Shells: Approximate Theory and Experiment

The low-frequency echo from finite ring-stiffened double cylindrical shells is studied.An approximate prediction method is proposed and validated by experiment.The method divides the echo into two parts:the elastic echo and the geometric echo.The elastic part is approximated by the elastic backscattering from finite double cylindrical shell with the internal water layer and derived by thin shell theory.And the geometric part is approximated by the geometric echo from analogous corner reflectors composed of shell and rings.The total echo can be obtained by adding up the two echoes in intensity.The range of ka is about 5～10 in the experiment.The formation mechanisms of different echoes are analyzed by the comparison between experimental and theoretical frequencyangle spectra.Finally,the measured Target Strength (TS) and approximate theoretical prediction are compared and the result shows that they are in good agreement in most angles.