﻿ 大型船舶机械噪声数值计算的液舱模拟方法
 舰船科学技术  2022, Vol. 44 Issue (24): 16-21    DOI: 10.3404/j.issn.1672-7649.2022.24.004 PDF

1. 中国船舶及海洋工程设计研究院，上海 200011;
2. 广船国际有限公司，广东 广州 510000

Tank modeling method for calculating mechanical noise of large ships
FENG Shuo-qiu1, WANG Yu1, CHEN Lin1, PENG Jing2
1. Marine Design and Research Institute of China, Shanghai 200011, China;
2. Guangzhou Shipyard International Co., Ltd., Guangzhou 510000, China
Abstract: Based on the principle of sound-structure coupling, a tank modeling method suitable for calculation of mechanical noise of large ships is proposed. Firstly, a typical model of three cabin is established, and the influence of different tank modeling methods on the simulation of mechanical noise is analyzed, and a "hybrid modeling method for tanks" is proposed. Secondly, the validity of the hybrid tank modeling method is verified by taking a typical model of three cabin and a real ship's model as examples. Finally, based on the hybrid tank modeling method, the mechanical noise prediction under the excitation of a certain ship's main engine is carried out. The research shows that the hybrid tank modeling method can take into account the calculation efficiency and calculation accuracy, meet the requirements of engineering forecast, and can provide a reference for the simulation calculation of mechanical noise of large ships.
Key words: large ships     mechanical noise     acoustic-structure interaction     tank modeling
0 引　言

1 船舶机械噪声计算的液舱模拟方法 1.1 声固耦合计算原理

 $\left[ {{{\boldsymbol{M_s}}}} \right]\left[ {\ddot U} \right] + \left[ {{{\boldsymbol{C_s}}}} \right]\left\{ {\dot U} \right\} + \left[ {{{\boldsymbol{K_s}}}} \right]\left\{ U \right\} = \left\{ {{{\boldsymbol{F_s}}}} \right\}。$ (1)

 ${\nabla ^2}p = \frac{1}{{{c^2}}}\frac{{{\partial ^2}p}}{{{\partial ^2}t}} 。$ (2)

 $\begin{array}{*{20}{l}} & \left[ {\begin{array}{*{20}{l}} {\left[ {{M_s}} \right]}&{\left[ 0 \right]} \\ {{\rho _f}\left[ R \right]}&{\left[ {{M_f}} \right]} \end{array}} \right]\left\{ {\begin{array}{*{20}{c}} {\left\{ {\ddot U} \right\}} \\ {\left\{ {\ddot P} \right\}} \end{array}} \right\} + \\ & \left[ {\begin{array}{*{20}{c}} {\left[ {{C_s}} \right]}&{\left[ 0 \right]} \\ {\left[ 0 \right]}&{\left[ {{C_f}} \right]} \end{array}} \right]\left\{ {\begin{array}{*{20}{c}} {\left\{ {\dot U} \right\}} \\ {\left\{ {\dot P} \right\}} \end{array}} \right\} +\\ & \left[ {\begin{array}{*{20}{c}} {\left[ {{K_s}} \right]}&{ - {{\left[ R \right]}^T}} \\ {\left[ 0 \right]}&{\left[ {{K_f}} \right]} \end{array}} \right] \left[ {\begin{array}{*{20}{c}} {\left\{ U \right\}} \\ {\left\{ P \right\}} \end{array}} \right] = \left\{ {\begin{array}{*{20}{c}} {\left\{ {{F_s}} \right\}} \\ {\left\{ 0 \right\}} \end{array}} \right\}。\end{array}$ (3)

 \begin{aligned}[b] & p\left(\overrightarrow{{r}_{p}}\right)=\alpha \left(\stackrel{\rightharpoonup }{{r}_{p}}\right)\displaystyle \underset{S}{\iint }\\ & \left[p\left(\stackrel{\rightharpoonup }{{r}_{q}}\right)\frac{\partial G\left(\stackrel{\rightharpoonup }{{r}_{p}},\stackrel{\rightharpoonup }{{r}_{q}}\right)}{\partial n}-G\left(\stackrel{\rightharpoonup }{{r}_{p}},\stackrel{\rightharpoonup }{{r}_{q}}\right)\frac{\partial p\left(\stackrel{\rightharpoonup }{{r}_{p}}\right)}{\partial n}\right]{\rm{d}}S\left(\stackrel{\rightharpoonup }{{r}_{q}}\right) 。\end{aligned} (4)

 ${{P_f}} = A {{P_s}} + B {P_{s,n}'}\; C {P_s} = D {P_{s,n}'} 。$ (5)

 $\left\{ {{P_f}} \right\} = \left( {\left[ A \right]{{\left[ C \right]}^{ - 1}}\left[ D \right] + \left[ B \right]} \right)\left\{ {P_{s,n}'} \right\}。$ (6)
1.2 考虑液舱影响的典型三舱段模型声固耦合数值计算

1）质量点法

2）源汇法

3）声学单元法

1.2.1 船舶典型三舱段模型

 图 1 典型三舱段模型示意图 Fig. 1 Schematic diagram of a typical three-cabin model
1.2.2 船舶典型三舱段声固耦合计算模型

 图 2 辐射噪声计算模型（半剖视图） Fig. 2 Radiated noise calculation model (half view)

1.2.3 计算结果及分析

1）模态计算结果

2）水下辐射噪声计算结果

 图 3 水下辐射噪声计算结果 Fig. 3 The calculation results of the underwater radiated noise

3）计算效率

1.3 液舱杂交模拟方法

2 液舱杂交模拟方法有效性研究 2.1 船舶典型三舱段模型水下辐射噪声计算 2.1.1 船舶典型三舱段水下辐射噪声计算模型

 图 4 典型三舱段有限元模型 Fig. 4 Typical finite element model of three cabins
2.1.2 计算结果及分析

 图 5 水下辐射噪声计算结果 Fig. 5 The calculation results of the underwater radiated noise

2.2 某船舱段模型水下辐射噪声计算 2.2.1 某船舱段水下辐射噪声计算模型

 图 6 某船舱段有限元模型 Fig. 6 Finite element model of a cabin section of a ship
2.2.2 计算工况

 图 7 舱段有限元模型（半剖视图） Fig. 7 Finite element model of cabin (half view)
2.2.3 计算结果及分析

 图 8 舱段水下辐射噪声计算 Fig. 8 Calculation of underwater radiated noise in the cabin
3 某大型船舶主机激励下的机械噪声计算 3.1 某船机械噪声计算模型

 图 9 某船机械噪声计算模型 Fig. 9 Calculation model of mechanical noise of a ship

3.2 激励载荷

 图 10 机脚振动加速度 Fig. 10 The vibration acceleration of the machine foot
3.3 计算结果及分析

 图 11 主机激励下的某船机械噪声计算结果 Fig. 11 Calculation results of mechanical noise of a ship under the excitation of the main engine

 图 12 不同频率下的声场分布 Fig. 12 Sound field distribution at different frequencies
4 结　语

1）相比于声学单元法、质量点法和源汇法，液舱杂交模拟方法能够兼顾计算精度和计算效率，适用于大型船舶的机械噪声计算中的液舱模拟。

2）针对三舱段模型的辐射噪声计算，杂交建模方法与声学单元法的计算结果吻合良好，总级偏差1.2 dB，计算时间缩短37.5%。

3）针对某船舱段模型的辐射噪声计算，杂交建模方法低于质量点法的声功率总级约1.3 dB，能够反映液舱中液体的阻尼效应。

4）采用杂交液舱模拟法模拟液舱中液体，计算得到某船主机引起的水下辐射噪声为150.0 dB。

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