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 应用科技  2018, Vol. 45 Issue (5): 10-15, 9  DOI: 10.11991/yykj.201802003 0

### 引用本文

SONG Feng, LI Wei. Simulation study on acoustic scattering characteristics of underwater composite rudder[J]. Applied Science and Technology, 2018, 45(5), 10-15, 9. DOI: 10.11991/yykj.201802003.

### 文章历史

1. 华中科技大学 船舶与海洋工程学院，湖北 武汉 430074;
2. 高新船舶与深海开发装备协同创新中心，上海 200240

Simulation study on acoustic scattering characteristics of underwater composite rudder
SONG Feng1, LI Wei1,2
1. School of Naval Architecture and Ocean Engineering, Huazhong University of Science and Technology, Wuhan 430074, China;
2. Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration (CISSE), Shanghai 200240, China
Abstract: In order to investigate the influence of composite material on acoustic scattering characteristics of rudder structure, apply the acoustic finite element method that combines automatically matched layer technique, as well as the acoustic computation software LMS Virtual Lab, and take the steel rudder model as the original reference to solve the acoustic scattering of the composite rudder and make a comparative analysis of it. The computation includes the abeam target strength, near-field scattering pressure for different incident angles and the directivity patterns of circumferential acoustic scattering target strength (TS) of two rudder models on horizontal plane. The results indicate that the TS of composite rudder is obviously lower than that of steel one in middle-high frequency, and the magnitude of directivity patterns of composite rudder is also lower in most directions. In addition, the strong scattering field occurs on the back of composite rudder but the steel model shows strong echo.
Keywords: finite element method    automatically matched layer technique    acoustic scattering    rudder structure    composite materials    acoustic pressure    target strength    scattering echo

1 声学有限元理论 1.1 有限元理论

 ${\nabla ^2}p + {k^2}p = 0$ (1)

 $\begin{array}{l}\int_\Omega {\nabla w \cdot \nabla p{\rm{d}}} \varOmega - {k^2}\int_\Omega {w \cdot p{\rm{d}}} \varOmega + {\rm{j}}\rho \omega \int_{{\varGamma _N}} {w{v_n}{\rm{d}}} \varGamma + \\{\rm{j}}\rho \omega {A_n}\int_{{\varGamma _R}} {wp{\rm{d}}\varGamma {\rm{ = 0}}} \end{array}$ (2)

 $p(r) = \sum\limits_{i = 1}^n {{N_i}(r){p_i} = N(r)p}$ (3)

 $\left[ {{K} - {k^2}{M} + {\rm{j}}\rho \omega {C}} \right]{p} = - {\rm{j}}\rho \omega {F}$ (4)

1.2 自动匹配层(automatically matched layer, AML)技术

2 计算流程及验证 2.1 计算流程

 ${T_S} = 20{\log _{10}}\frac{{{P_r}}}{{{P_i}}}\left| {_{r = 1}} \right.$

2.2 单层球壳模型验证

3 舵结构声散射分析 3.1 模型

 $E = 1.102 \times {10^7} + 5\,\,447.2f - 3.515 \times {10^{ - 2}}{f^2}$ (5)
 $\eta = 0.401 + 1.21 \times {10^{ - 4}}f - 3.29 \times {10^{ - 9}}{f^2}$ (6)

3.2 正横目标强度

3.3 不同角度入射时的散射声压

3.4 目标强度的指向性