Investigation On The Resistance And Wave-maker Of Submarine Traveling In A Stratified Marine Environment

Due to the complexity of the ocean,the light and the depth of the seawater will cause salt and heat in the depth of the ocean distributing unevenly,resulting in a wide range of different types of pycnoclines in the ocean.When the submarine sails around the pycnoclines,the hull disturbs the surrounding fluid to excite the internal wave field,which increases the submarine's navigation resistance.The flow field induced by the internal interface will interact with the free surface flow field to form a discernible fold.With the above problems as the background,for the complex fluid-structure coupling problem of submarine sailing in a stratified ocean environment,this paper uses the computational fluid dynamics(CFD)software STARCCM + to study the submarine navigation resistance and wake field characteristics.First of all,using physical model experiments and numerical methods,the resistance and wave-free wave generation at different depths and Froude numbers of the submarine are studied.The numerical results agree well with the experimental results,indicating the effectiveness of the numerical method.Further,the relationship between the resistance and the speed under different depths is analyzed.The results show that when the depth is large,the resistance of the submarine with the Froude number changes to a second power relationship.When the diving depth is shallow and the Froude number is high,the effect of wave-making resistance is significant.Since the wave-making resistance is usually proportional to the change of the Froude number to the power of 4-6,the correlation of quadratic polynomial fitting decreases.On the basis of the above research,the three-phase flow method is further used to simulate the submarine navigation in the stratified marine environment using the SUBOFF model.The renormalization group turbulence model was used to close the turbulence equation,the internal interface and wave motion were captured based on the volume fraction function of the fluid,and the navigation resistance of the density submarine submarine and the wave-making characteristics of the internal interface and free surface were studied.The effects of different sailing speeds,relative internal interface positions,submarine relative submersible depth,upper and lower fluid density ratios on sailing resistance and wave-making characteristics were investigated respectively.The resistance results show that under different submarine relative internal interface position conditions,the overall submarine navigation resistance coefficient Cd increases with the inner Froude number,and thenincreases first and then decreases.The navigation resistance reaches the maximum value at Fr= 0.9,and the resistance coefficient Cd remains basically unchanged after Fr> 2.0.At low speed,the navigation resistance coefficient is larger at the relative depth of-0.5d,followed by the relative depth of + 0.5d,and the relative depth of 0 is the smallest.In the high-speed state,the resistance coefficient curve basically does not change with the change of the inner Froude number.When the relative diving depth is 0,the resistance coefficient is the largest,the relative diving depth is-0.5d,and the relative diving depth + 0.5d is the smallest.In general,the internal interface has a certain effect on the submarine's navigation resistance,especially at low speeds.The numerical results of submarine wave-making show that under the condition of low speed,Fr <Fr2,the phenomenon of internal interface shear wave is obvious,and the wavelength is short.As the sailing speed increases,the peak value of the internal wave making waves gradually increases;the trough value decreases as the sailing speed increases.The wave height gradually decreases as the sailing speed increases.As the speed increases,Fr> Fr2,only scattered waves exist at the internal interface.The wavelength increases with speed.The internal interface has little effect on the free liquid surface wave.The relative position and peak valley value of the peak and valley of the two-phase flow and the three-phase flow are basically unchanged.When the relative diving depth is 0 and-0.5d,under the condition of high navigation speed,the free A recognizable water surface wake appeared on the surface.