Research On Hydrodynamic Characteristics Of Underwater Launching And Seawater Reinjection Of Vehicle

Compared with land-based launching and space-based launching,the launch environment of submarine-launched vehicles is extremely complicated because they are located in the depths of the ocean.At present,only a few countries have mastered the mature underwater launching technology.Therefore,the research on the vertical launch of underwater vehicles has important meaning.Based on fluid simulation software STARCCM+,the evolution law of gas-water two-phase flow field and seawater recharge process after the tail exit of underwater vertical launch vehicle were numericized,and the evolution law of the formation,development and collapse process of the air bubble in the launching barrel nozzle was studied.On this basis,the influence of the velocity and cross flow on the motion characteristics of the vehicle and the effect of "water hammer" on the launching cylinder are further studied.The results show that:1.Without considering the influence of cross flow,lid opening mechanism and vehicle,the recharging process of launching cylinder can be divided into three stages.With the increase of initial internal and external pressure difference,the fluctuation amplitude of pressure load in the cylinder increases,and the fluctuation period slightly decreases.Under the condition of a certain initial pressure difference between inside and outside,the environmental water depth has no effect on the load amplitude of barrel bottom,but the fluctuation frequency of barrel bottom load increases with the increase of water depth.2.With the increase of the exit velocity of the vehicle,the volume of the air bubble at the exit of the tube increases,and its evolution law remains basically unchanged.The strength of the central axis return jet increases,the axial impact load at the bottom of the tube increases,and the fluctuation period increases slightly.Under the influence of the transverse incoming flow,the tail cavitation of the vehicle presents asymmetry,which leads to the asymmetry of the tail load,and then causes the attitude change of the vehicle.The impact load of axial force at the bottom of tube has no obvious relation with the velocity of cross flow.3.In the salvo condition,the air bubble of the first tube moves downstream and fuses with the air bubble of the second tube,which improves the launching environment of the second launch vehicle.The tail cavitation asymmetry of the second launch vehicle is weaker than that of the first launch vehicle,so the ballistic stability of the second launch vehicle is better.For the launching tube,the peak value and fluctuation frequency of the shock load of seawater recharge in the first and the second launching tube are basically the same.