水下潜器首部声基阵区流噪声研究方法

水下潜器在航行过程中,主要使用声呐来探测敌方舰艇以及自身位置.主声呐一般安放在潜艇首部位置,可分为主动声呐与被动声呐.在探测目标时,噪声是2种声呐系统都必须克服的干扰因素.针对自噪声中的流噪声,首先使用LES模型对水下潜器的外流场进行仿真计算.在获得流场中的脉动压力分布后,将其导入基于Lighthill声类比理论的声学软件ACTRAN中进行声场仿真计算,实现了对水下潜器首部声基阵区流噪声的数值预报.研究了航速、共形阵的安装位置和基阵单元安装面形状对声基阵区流噪声传播的影响.结果表明:航速越大,流噪声越大;增大声呐安装面与导流罩的距离以及使用较光滑的安装面,可以减小声基阵区流噪声的大小.     

有限元法在非线性波浪与结构物相互作用中的应用(英文)

We review recent advances in the finite element method (FEM) simulations of interactions between waves and structures. Our focus is on the potential theory with the fully nonlinear or second-order boundary condition. The present paper has six sections. A review of previous work on interactions between waves and ocean structures is presented in Section one. Section two gives the mathematical formulation. In Section three, the finite element discretization, mesh generation and the finite element linear system solution methods are described. Section four presents numerical methods including time marching schemes, computation of velocity, remeshing and smoothing techniques and numerical radiation conditions. The application of the FEM to the wave-structure interactions are presented in Section five followed by the concluding remarks in Section six.