Research On Cavitation Multiphase Flow And Ballistic Characteristics Of Parallel High Speed Projectile Under Water

Supercavitation drag reduction technology is a kind of underwater weapon drag reduction technology that has received much attention in recent years.The high-speed supercavitating projectile designed by this technology is mainly applied to antitorpedo and anti-mine warfare combat systems.Parallel supercavitating projectiles have complex flow phenomena such as passing through free surface,cavitation,turbulence,tail slap,etc.and during high-speed entering water or underwater movement,it will form a complex multiphase flow field which is composed of gas,vapor and liquid media.Parallel projectiles also have the interaction of multi-elastic mutual disturbance and the coupling effect of flow field and motion,which are a typical type of dynamic fluid-solid coupling interaction problem.Therefore,the research on characteristics of multi-phase flow field and ballistic characteristics of parallel high-speed projectiles has important theoretical significance and application value.In this paper,theoretical analysis,numerical simulation and experimental research are combined to study the multiphase flow field and ballistic characteristics of high-speed projectiles in horizontal motion.The specific research contents are as follows:Based on the RANS equation,introducing VOF multiphase flow model to describe gas-water interface,introducing cavitation mass transport equation to describe cavitation,using overlapping grid method and six-degree-of-freedom motion model to describe the coupling between flow field and motion.A numerical simulation method for multi-phase flow 、 fluid dynamics and motion trajectory calculation of underwater projectile parallel motion is established.And the experimental data is used to verify the effectiveness of the numerical simulation method.A free-flight experiment of underwater parallel motion of high-speed projectiles was carried out using a high-speed projectile underwater parallel motion launcher based on gas dynamics.The image data of underwater parallel motion of high-speed projectile is obtained by high-speed camera measurement,and the time-varying history of projectile velocity,trajectory and attitude is obtained by processing the image data.The multi-phase flow field evolution characteristics of hollow bubble generation,development,closure and shedding during high-speed projectile synchronization and asynchronous underwater parallel motion are also given.The underwater ballistic characteristics and tail motion characteristics of the projectile are analyzed.The influence of phase flow field characteristics and ballistic characteristics,and the instability state of a typical head-type projectile underwater parallel motion.The numerical simulation of underwater parallel motion of high-speed projectile is carried out according to the experimental conditions.The multi-phase flow field characteristics and hydrodynamic characteristics of high-speed projectile underwater parallel parallel motion are studied.The mechanism of the attitude change of the projectile in parallel parallel water entering process is revealed..On this basis,the evolution mechanism of the asynchronous parallel projectile cavitation and the influence of the launch time difference on the ballistic characteristics of the highspeed projectile underwater parallel parallel motion are analyzed.