Numerical Analysis And Research On Hydrodynamic Noise Of An Underwater Vehicle

The underwater vehicle is an underwater weapon.Ensuring the concealment and quietness of the underwater vehicle is the focus of the research.In response to this problem,this article is based on the STAR-CCM+ fluid software to analyze the flow field characteristics of the underwater vehicle.Based on the LMS Virtual.lab software,the boundary element method(BEM)is used to calculate the hydrodynamic noise of the aircraft with the wall pressure pulse as the noise source.The details are as follows:(1)Based on the RANS method and the RNG k-ε turbulence model,this paper takes the underwater vehicle as the research object,calculates the shell pressure of the underwater vehicle under different flow speed conditions;summarizes the pressure change law of the nose of the vehicle;Discuss the law of underwater vehicle speed change;use Curle equation to calculate the sound pressure level at the apex of the nose,and the sound pressure value tends to decrease gradually with the increase of frequency.(2)Using the fluctuating pressure of the shell as the dipole sound source of noise radiation,the flow noise of the underwater vehicle is calculated by the boundary element method,and the cloud diagram of the sound pressure change of the underwater vehicle at different frequencies is simulated;The sound power level spectrum at different incoming velocities and different water depths;the boundary element method and the Curle equation are used to calculate the sound pressure level of the characteristic points,which proves the correctness of the calculation model;the increase in the sound pressure level of the characteristic points along the axial direction with distance is discussed The degree of severity is large and reduced,and it is concluded that the flow noise of the aircraft decays faster in the near-field area.(3)Based on the LMS Virtual.lab software,the vibration displacement of the underwater vehicle is solved,and the vibration acceleration is calculated by obtaining the two derivatives,which is used as the fourth-level sub-sound source to simulate the flow-induced noise of the underwater vehicle;The sound pressure cloud diagrams of flow noise and flow-induced noise are larger than flow noise at each frequency;for 12 characteristic points,with increasing distance,the sound pressure level shows a decreasing trend,which is co MParable to the sound pressure of flow noise at the same frequency.The change trend of the level with distance is the same.In the near-field area,the sound pressure level of flow noise decreases faster.The hydrodynamic noise is comprehensively predicted,and it is concluded that the flow-induced noise occupies a dominant position.(4)The boundary element method was used to calculate the hydrodynamic noise of three types of aircraft with different front-end shapes: cusp(45°),cusp(30°),and arcshaped.Through the co MParison of the sound pressure cloud diagrams of various working conditions and the sound pressure levels of a series of characteristic points,the discussion The contribution of flow noise and flow-induced noise to the total noise radiation under different front-end shape conditions is summarized,and it is concluded that the front end of the aircraft is pointed(45°)with the largest radiation noise.The variation law of the vehicle radiated noise obtained by simulation is accurate and feasible.The law obtained in this paper will provide references for the vibration and noise reduction and design of underwater vehicles.