Numerical Study Of Mechanical Properties Of Transmedium Missile During Water Exit

With the gradual development of Marine resources,people pay more and more attention to the ocean,the competition for maritime rights and interests has become a hot spot,and the naval equipment of various countries is developing continuously.Submarine-launched missile(SLBM)has become a weapon developed by many countries due to its superior operational performance.However,complex multiphase flow exists in the process of SLBM coming out of water,which makes it difficult to maintain the stability of attitude and the integrity of structure.Based on FLUENT software platform and computational fluid dynamics method,this paper carries out numerical research on the outflow process of Submarine-launched missile,and obtains the characteristics of the force and movement of the missile in the water exit process,which provides reference for engineering design.Firstly,through the calculation of the steady cavitation of the rotating body,the ability of different models to capture the details of the cavitation flow field is discussed,so as to determine the appropriate calculation model.And,the vertical water exit process of slender body was verified to confirm the applicability of the calculation model for multi-degree-of-freedom motion analysis.In addition,the vertical water exit of axisymmetric rotary body is studied and the collapse mechanism of cavitation is analyzed.Second,one submarine-launched missiles of the United States navy model was created,and carried out three-dimensional slope water and cold missile launch process numerical research,compared the initial velocity and Angle of water exit process and the Angle of attack for missile across the medium flow field characteristics,mechanical characteristics and movement characteristics,and found that during water exit process,the cavitation collapse shows asymmetric,As a result,the load on the missile appears peaks in opposite directions.In addition,the larger the velocity of missile is,the larger the cavitation area on the side of the missile body will be,and the stronger impact load will be generated when the cavitation collapse.The water exit Angle has little influence on the distribution of cavitation,but when the water exit Angle becomes smaller,the time interval for the collapse of the upper and lower sides of the missile will become larger,resulting in the asymmetric effect of the missile.The attack angle results in asymmetric cavitation distribution,and the side with larger volume of cavitation is subjected to stronger effect.Finally,based on the above methods,a numerical study on vertical water exit process of thermal launch missile is carried out.Based on the calculation model of water exit of the missile body,the ideal gas model is introduced to obtain the development process of shoulder cavitation region,tail cavitation region,gas bubble development process and the pressure distribution law of the missile’s surface during the water exit process of the thermal launch missile.In addition,the influence of the velocity during the water exit process of thermal launch missile is compared.The results show that the gas jet at the tail of the missile leads to the increase of the pressure at the tail of the missile,which leads to the increase of the normal flow force at the tail of the missile,and the tail high pressure gradually disappears with the development of the gas bubble.As the projectile body approaches the free surface,the cavitation zone disappears,and the change law of impact load produced when the cavitation zone disappears is consistent with that of cold launch.During the development of gas jet,the necking phenomenon occurs due to the influence of water.When the velocity is large,the cavitation area at the tail merges with the gas bubble,forming a constantly changing bubble.