Numerical Simulation Analysis Of Flow Noise Of Typical Underwater Structure

When the underwater vehicle is in motion,it will change the motion state of the fluid around it,which will let fluid in an unstable state.The change of the density of the surrounding medium caused by the instability of fluid motion will lead to noise,which is called flow noise.Flow noise affects the concealment of underwater vehicles seriously,so studying the generation and characteristics of flow-induced noise has great significance.Because it is difficult to carry out the experimental study of flow-induced noise,using simulation software to study this kind of problem is a good choice.Because the structure of underwater vehicle is complex,and the shape is diverse,so this paper takes bluff body,streamline body and revolving body as the research object,and uses ANSYS to simulate the flow field and flow noise of the three structures.The simulation is divided into two parts.In the first part,the two-dimensional numerical simulation of the flow field around different structures in the flowing fluid is carried out,and the flow noise of the flow field is calculated.The simulation results show that when the object is stationary,the noise radiation around the flow field is mainly dipole type,which accords with the Curle’s theory.According to the sound pressure level spectrum of noise,it can be found that the flow noise is mainly low-frequency noise.In the second part,the two-dimensional and three-dimensional numerical simulation of the flow field around different structures in motion is carried out,and the simulation results are summarized.Through the simulation results,it can be found that the noise radiation generated by moving objects around the flow field is mainly monopole type,which is consistent with the theory of Ffowcs Williams and Hawkings.According to the sound pressure level spectrum of noise,it can be found that the flow noise is mainly high frequency noise.In this paper,the flow noise caused by moving object in fluid medium and the flow noise caused by static object in flowing fluid are studied by using finite element software.The results show that the distribution of the flow field around a stationary object in flowing fluid is obviously different from that around a moving object in stationary medium.The flow noise generated by the two models is also different.