Research On Supercavitation Flow And Hydrodynamic Characteristics Of High-speed Projectiles Entering Water Accompanied With Waves

The problem of supercavitating flow of high-speed projectiles entering water under wave conditions arises from the naval battle scenario of supercavitating weapons attacking underwater targets and has important engineering significance.During the process of high-speed object entering water under wave environment,it involves complex multiphase flow phenomena such as interfacial crossing,cavitation,turbulent flow,and coupling between the projectile and supercavitation.It has strong instantaneousness and nonlinearity,and these problems have been rarely studied in detail until now.In this thesis,a systematic study of the supercavitating flow characteristics of high-speed projectiles entering water under wave conditions was carried out using a combination of numerical calculation and theoretical analysis,with a focus on analyzing the flow field characteristics and projectile motion characteristics.The main innovations of this paper include:(1)For the problem of single and successively fired projectiles entering water at high speed under wave conditions,the second-order Stokes wave is defined through programming.The six-degree-of-freedom trajectory model is introduced,and the initial six-degree-of-freedom attribute parameters of the projectile are programmed to systematically analyze the projectile’s motion characteristics after entering the water under wave conditions.(2)The process of cavity expansion and collapse under wave conditions was quantitatively analyzed,and a series of parameters were defined to describe the cavity’s shape characteristics under wave conditions.The main research conclusions of this paper are as follows:(1)This study investigates the multiphase flow characteristics of successively fired projectiles entering water under different wave conditions,wave heights,and velocities.For single-fired projectiles,the maximum load peak occurs when the projectile enters at 0° phase,and the minimum peak occurs at 180° phase.The load peak of the rear-fired projectile is much smaller than that of the front-fired projectile at all wave phases for successively fired projectiles.The splash patterns are similar in both single-fired and successively fired scenarios,with the splash tending to go in the opposite direction of wave propagation at 0° phase and towards the wave propagation direction at 180° phase.(2)For wave heights,the load peak decreases as the wave height increases for single-fired projectiles,and the lateral displacement and yaw angle of both front-fired and rear-fired projectiles increase with increasing wave height for successively fired projectiles.The larger the wave height,the earlier the surface closure of the air cavity occurs.(3)For projectile velocities,the load peak increases with increasing velocity for single-fired projectiles,and the rear-fired projectile experiences an earlier velocity attenuation due to the interaction with the upward jet created by the front-fired projectile in the successively fired scenario.The air cavity closure time is slower at higher velocities,and the maximum non-dimensional radius and length of the air cavity on the impingement side and the wake side increase.