﻿ 舰船开孔流动噪声控制措施研究
 舰船科学技术  2017, Vol. 39 Issue (9): 35-39 PDF

1. 海军驻武汉七一九所军事代表室，湖北 武汉 430074;
2. 武汉第二船舶设计研究所，湖北 武汉 430205

Control measures for hydrodynamic noise of water hole on ship
LI Sheng1, HUA Ru-nan2, XU Jun2
1. Military Representative Office of Navy in 719 Research Institute, Wuhan 430074, China;
2. Wuhan Second Ship Design and Research Institute, Wuhan 430205, China
Abstract: In order to study the characteristics of hydrodynamic noise of water hole, the flow field round the three-dimensional water hole model was numerical simulated based on the large eddy simulation. Then the flow noise was calculated by the boundary element method and the control measures of flow noise was analyzed. It is shown that the change of water hole parameters would directly affect the level of flow noise, which could provide reference for noise reduction design of water hole on ship.
Key words: water hole     flow noise     control measure     large eddy simulation
0 引　言

1 计算方法和程序验证 1.1 计算方法

 $\left\{ {\begin{split}& {\displaystyle\frac{\partial }{{\partial {x_i}}}\left( {{{\bar u}_i}} \right) = 0}\text{，} \\& {\displaystyle\frac{\partial }{{\partial t}}\left( {{{\bar u}_i}} \right) + \frac{\partial }{{\partial {x_j}}}\left( {{{\bar u}_i}{{\bar u}_j}} \right) = - \frac{1}{\rho }\frac{{\partial p}}{{\partial {x_i}}} + \nu \frac{{{\partial ^2}{{\bar u}_i}}}{{\partial {x_i}\partial {x_j}}} - \frac{{\partial {\tau _{ij}}}}{{\partial {x_i}}}}\text{。} \end{split}} \right.$ (1)

 ${\tau _{ij}} = {\bar u_i}{\bar u_j} - {\bar u_i}{\bar u_j}\text{。}$ (2)

 ${\tau _{ij}} = - 2{\nu _t}{\bar S_{ij}} = - 2C_s^2{\Delta ^2}\left| {\bar S} \right|{\bar S_{ij}}\text{，}$ (3)
 $\left| {\bar S} \right| = \sqrt {2{{\bar S}_{ij}}{{\bar S}_{ij}}}\text{。}$ (4)

 ${\bar S_{ij}} = \frac{1}{2}\left( {\frac{{\partial {{\bar u}_i}}}{{\partial {x_j}}} + \frac{{\partial {{\bar u}_j}}}{{\partial {x_i}}}} \right)\text{。}$ (5)

 $\frac{1}{{a_0^2}}\frac{{{\partial ^2}p}}{{\partial {t^2}}} \!-\! {\nabla ^2}p = \frac{\partial }{{\partial t}}\left[ {{\rho _0}{u_n}\delta (f)} \right] \!+\! \frac{{{\partial ^2}}}{{\partial {x_i}\partial {x_j}}}{T_{ij}} - \frac{\partial }{{\partial {x_i}}}\left[ {{P_{ij}}{n_j}\delta (f)} \right]\text{，}$ (6)

 ${P_{ij}} = p{\delta _{ij}} - \mu \left[ {\frac{{\partial {u_i}}}{{\partial {x_j}}} + \frac{{\partial {u_j}}}{{\partial {x_i}}} - \frac{2}{3}\frac{{\partial {u_k}}}{{\partial {x_k}}}{\delta _{ij}}} \right]\text{。}$ (7)
1.2 程序验证

 图 1 U=9 m/s算例采样点的压力级频谱 Fig. 1 Pressure level spectrum of a sample point for case U=9 m/s

 图 2 U=30 m/s算例采样点的压力级频谱 Fig. 2 Pressure level spectrum of a sample point for case U=30 m/s
2 计算结果与讨论

2.1 不同结构加强形式的影响

 图 3 开孔2种结构加强形式 Fig. 3 Hole with two types of structure

 图 4 两种结构加强方式开孔监测点脉动压力频谱 Fig. 4 Pressure spectrum of a sample point for two types of structure

 图 5 两种结构加强方式开孔辐射噪声频谱 Fig. 5 Sound pressure level spectrum of a sample point for two types of structure

2.2 开孔流噪声控制措施及效果分析

2.2.1 增装导流体

 图 6 两种带导流板的开孔模型 Fig. 6 Hole with two types of deflector

 图 7 不同尺寸导流体的开孔噪声控制效果 Fig. 7 Comparisons of noise reduction for different deflectors

 图 8 导流体降噪示意图 Fig. 8 Sketch of noise reduction for deflectors
2.2.2 增装圆形挡板

 图 9 三种尺寸圆柱挡板示意图 Fig. 9 Sketch of three kinds of size for circular baffle

 图 10 不同尺寸圆柱挡板的开孔噪声控制效果对比 Fig. 10 Comparisons of noise reduction for different circular baffles

 图 11 圆形挡板降噪示意图 Fig. 11 Sketch of noise reduction for circular baffles
3 结　语

本文以舰船表面开孔为研究对象，通过对不同开孔形式的流体激励及流噪声特性进行数值仿真计算，得到以下结论：开孔沿横向或流向方向结构加强对流体直发声辐射噪声总级影响不大；沿流向方向结构加强开孔引起的流体激励频率更加丰富，且幅值较高，建议开孔结构加强方式采用横向加强方式；在开孔前缘增加导流体、开孔下方增设圆形挡板均能有效的降低流体直发声，且随着导流体的高度增加，圆形挡板越深，流体直发声的降噪效果越明显；增设导流体的降噪方式使得流体主要激励频率往更低频发展；增设圆形挡板对流体激励频率影响不大，但挡板高度越高，脉动压力幅值明显增加，采用此种降噪方式需综合考虑流激结构振动噪声的影响。

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