毕业论文移动版

摘要潜艇产生的辐射噪声是影响潜艇隐蔽性能的重要因素之一。潜艇噪声是以声波 的形式在水下进行传播的，因为潜艇的噪声对于潜艇的隐蔽性的影响是巨大的。如 果能够对潜艇的辐射噪声进行有效的预报，对于潜艇的本身的隐身性能的设计及优 化来说都有重要的意义。77836

出动潜艇进行实艇试验，虽然结果最为可靠，但需要大量的人力、物力，成本 十分高昂。而通过数值仿真与小型实验相结合，即采用数值仿真计算出潜艇受周期 力激励的频响曲线，结合实验测量艇载机械设备的激励强度，可以有效的对潜艇的 振动与声辐射进行预报，甚至是实现实时预报。

本文利用有限元结合边界元的思想，利用有限元软件进行建模，采用计算程序 提取结构表面网格并建立声场边界元模型，建立基于有限元-边界元法的水下振动与 声辐射预报方程。利用有限元法对结构域进行离散，建立结构振动与力激励的关系 方程；采用边界元法对结构外部声场进行离散，建立结构表面振速与声压分布的关 系方程；最后通过流固耦合条件和振速连续条件将二者联立得到完备可解的矩阵方 程组。A、B 为边界元矩阵，p 为结构表面声压分布向量，设 q 为结构表面振速向量， 则边界元方程为：

Ap=Bq （1）Ap=Bq 求出来的是结构表面的声压，之后可以结合结构表面的声压和振速的关 系，通过 Helmholtz 积分求外部声场中的任意场点的声压。通过扫频求解绘制频响 曲线，结合机械设备实测激励数据，仅需要简单的乘法即可得出实际结构的声辐射 频率分布特性。

毕业论文关键词：有限元；边界元；声辐射；预报

Abstract The radiation noise generated by submarine is one of the important  factors  that affect the performance of submarine。 Submarine noise is carried out in the form of sound wave, because the influence of submarine noise on the submarine is huge。 If the radiation noise of the submarine can be effectively predicted, it has important significance for the design and optimization of the submarine's stealth performance。 In the process  of practical production, the high cost of real boat experiment。 If the radiation noise of the submarine can be effectively predicted, it has important significance for the design and optimization of the submarine's stealth performance。

Submarine test, although the results are most reliable, but requires a lot  of manpower and material resources, the cost is very high。 And through numerical simulation and small experimental combined the numerical simulation calculate submarine subjected to periodic force excitation frequency response curve,  combined with experimental measurements of airship incentive intensity of machinery and equipment, can be effective to the submarine vibration and sound radiation prediction, even to realize the real-time forecast。

The finite element software modeling and the program extraction structure surface grid was used by the finite element method and the boundary element method, which establish the acoustic boundary element model that based on finite element - boundary element method of underwater vibration and sound radiation prediction equation。 Using finite element method to discretize the domain and the relation equation of structure vibration and force excitation is established; on the external sound field of the structure is discretized by using boundary element method, structure surface vibration velocity and sound pressure distribution equation is established; the flow solid coupling condition and the vibration speed continuous conditions would simultaneous have got the complete solution of the matrix equations。 B, A is represented for the boundary element matrix, P is represented for the structure of the surface acoustic pressure distribution vector and Q is represented  for  the  structure  of  the  surface  vibration  velocity  vector,  the   boundary element equation is:Ap=BqAp=Bq for surface structure of sound pressure, can be based on the relationship between the surface structure of the sound pressure and particle velocity, the Helmholtz integral for external field of any points of sound pressure。 Through the swept frequency solving frequency response curve is drawn, combined with mechanical devices measured excitation data, only need a simple multiplication can draw the actual structure of the acoustic radiation frequency distribution characteristics。 (责任编辑：qin)