Research On The Drag & Noise Reduction Performance Of Submersible Skin Under Turbulent Excitation

Submarine,as an important part of the marine military forces,is always concerned by military experts.Under the new international situation and technical background,higher requirements for submarine maneuverability are put forward,smaller fluid resistance and noise radiation at high speed are hoped.In order to meet the need of combat in the new period and improve the overall combat capability and survival ability of the submarine,a variety of skin with drag and noise reduction has gradually become the research hotspot in related fields.In this paper,the necessity and feasibility of drag and noise reduction under turbulent excitation was analyzed,the progress of research on turbulence and submarine skin were reviewed.A flexible submarine skin with double-layer damping structure was designed.The characteristics of random vibration and noise reduction performance were in-depth studied.The main work of this paper is as follows:Firstly,according to the working principle and characteristics of the submerged skin,the design scheme of the flexible skin with double-layer vibration-damping structure was determined and its structure was designed in detail.The skin is mainly composed of the flexible surface confinement layer and the bilayer damping structure.The synergistic effect between the two can effectively can reduce the pulsating pressure of the turbulent boundary layer and suppress the turbulence burst phenomenon,thus achieving the effective control of the turbulence resistance and the flow noise.Secondly,the Fluent software was used to simulate the flow field around the submarine model.The pulsating pressure on the surface of the model was solved and the power spectral density was calculated by Fourier transform.Using the virtual excitation method and the finite element software,the power spectrum density was taken as input,the random vibration of the skin structure under turbulent pressure is analyzed.Then,the drag and noise reduction performance of the submerged skin was analyzed by the method of fluid-structure coupling.On the basis of random vibration analysis,the performance of the flexible skin was analyzed by fluid-structure interaction and acoustic analysis.The results show that:The design of the flexible skin structure can effectively control the turbulence resistance and noise.The mechanism of drag reduction and de-noising is that the deformation of the flexible surface decreases with the fluctuation of the pulsating pressure and the turbulence attenuation of the double-layer structure reduces the turbulence intensity.So that the flow resistance decreases and turbulence noise weakened.Finally,the influence of the main design parameters on the skin properties was studied.By adjusting the parameters of the model,the performance of the skin with different parameters was studied.The influence of the parameters on the skin properties was summarized: the increase of the material damping can improve the noise reduction performance of the skin,especially the low frequency noise reduction performance.The increase of the elastic modulus will decrease the overall performance of the skin.The quality of intermediate has little effect on the noise reduction performance of the skin,but a larger quality can be benefit to the stability of the system.In this paper,a flexible skin with double-layer damping structure was designed and its performance of drag and noise reduction was researched.This study can be used for the research and design of submarine skin in the future.