Research On The Influence Of Maneuver Mode On Submarine Hydrodynamic Wake

Seawater undergoes the influence of solar radiation and ocean currents and monsoons to stably stratify its vertical density,temperature and salinity,and ocean internal waves are internal fluctuations that occur in a stable stratified ocean.When the submarine is moving in a stable stratified ocean flow field,its own volume effect and turbulent wake will cause great disturbance to the stable stratified fluid,and this disturbance will bring the energy inside the ocean into the surface flow field.As a result,short gravity waves in the surface flow field and surface tension convergence and divergence effects are triggered.Because this feature is not easy to control by conventional methods,when the submarine is sailing in stable stratified seawater,the influence of its internal waves on the free surface can last for dozens of days.,The horizontal scale behind the hull is extremely large,which can be identified by the scattering intensity of the synthetic aperture radar(SAR)through the sea surface,which will have a greater impact on the navigation and concealment of the submarine.Combined with its distribution characteristics,the wake of the submarine body can be measured.Wide-range detection around the clock.In the early days,people only regarded internal waves as annoying"noise" to eliminate such signals,but Munk(1979)and Garrett thought it was a useful"signal".With the in-depth study of internal waves in modern times,people began Gradually discover the importance of internal wave signals in ocean observation,anti-submarine warfare,and submarine concealment.Based on typical ocean stratified environmental conditions and principles and methods of computational fluid dynamics,a numerical simulation method for strong stratified and continuous stratifief flows is established,mainly:the volumetric method of fluid(vof method)is used to capture the flow of free surface and inner interface and realize the difference Density fluid stratification;combined with the energy conservation equation and fluid state equation to establish a linear and continuous stratified numerical model of density with density;considering the anisotropy of turbulent buoyancy effects,the SST turbulence model is selected.First,study the influence of the submerged depth and the internal Froude number in the flow around a cylinder in the strong stratification on the amplitude and wavelength of the internal interface wave making.The critical Froude number for the maximum amplitude of the induced internal wave is obtained,and the calculated results are compared with the experimental values.,To verify the feasibility of CFD simulation of submerged body motion in stratified flow.Numerical simulation of the free surface wave making of a real-scale submarine in the continuous layered and strong layered oceans with a constant submerged depth and a fixed speed.The effects of different speeds and layered states on the amplitude of the free surface and the intensity of convergence and divergence are compared.The higher is,the higher the amplitude of the free-surface wave,the longer the wavelength,and the higher the intensity of the free-surface convergence and divergence,the easier it is for the submarine to be detected.Secondly,because the submarine often performs different forms of maneuvers during the movement in the ocean,such as accelerating and decelerating,snorkeling and diving,and accelerating and descending.Based on the research of submarine maneuvering methods in the literature on anti-submarine warfare and submarine safety navigation,different accelerations are selected to simulate the fluctuations of free surface wave making and internal interface wave making in a strong layered system by a real-scale submarine.Finally,the simulated submarine dives at different attitude angles in sea conditions.Combining the literature on safe navigation of submarines in dense cliffs,calculating the wave-making characteristics of the submarine’s motion on the free surface in the submersible maneuver mode,combined with the principle of radar detection,and using numerical calculation methods to obtain the submarine water in different layered oceans and different maneuvering modes.The amplitude and distribution characteristics of the convergence and divergence intensity of the surface flow field during the downward maneuver provide a theoretical basis for non-acoustic detection of submarine maneuvering modes.