Research On Cavitation And Hydrodynamic Characteristics Of Rotating Supercavitating Projectile In Water

At present,there are two ways to stabilize underwater high-speed projectiles.One is a large aspect ratio non-rotating projectile,which uses tail-slap effect to ensure stable underwater movement.The other is based on the principle of gyro stabilization,so that the underwater highspeed projectile has a rotational angular velocity during the movement to achieve high-speed stable movement requirements.Cavitation flow field and hydrodynamic characteristics of underwater high-speed rotating projectile are researched in this thesis,and stability of underwater high-speed rotating projectile in a certain configuration is analyzed and researched.The main research contents of this thesis are as follows:(1)The numerical calculation model for underwater high-speed supercavitating projectiles is established,which is based on Open FOAM combined with basic fluid control equations,6)- turbulence model,Schnerr-Sauer cavitation model and uniform equilibrium flow model,and the numerical model is verified.(2)For a typical underwater high-speed projectiles configuration,the effects of different rotational angular velocities(1000r/s,2000r/s,3000r/s,4000r/s),attack angles(0?5°)and nutation angles(0?5°)on the cavitation flow field characteristics and hydrodynamic forces of underwater high-speed rotating projectiles are analyzed under the condition of 500 m / s inflow velocity.(3)The numerical simulation of a certain underwater high-speed rotating projectiles is carried out.Combined with the characteristic number analysis method of the urgent screw stability of the external ballistic projectiles,the stability of its underwater motion is analyzed.(4)The water target test is carried out for a certain underwater high-speed rotating projectiles to verify the simulation results.The results show that for typical high-speed underwater projectiles configuration,at 0°angle of attack,when the incoming flow velocity is 500m/s,and the cavity is completely wrapped in the projectiles,the rotating angular velocity of projectiles has little effect on the cavity shape,and the drag coefficient increases with the increase of rotating speed,and the change of drag coefficient is mainly caused by the change of friction resistance.When the angle of attack is small,the drag coefficient and lift coefficient increases with the increase of the angle of attack.The influence of nutation angle on cavitation characteristics and flow field characteristics of projectiles is very complex.Generally speaking,the nutation motion increases the drag coefficient of the projectile,aggravates the wetting of rotating projectile,and causes larger pitching moment.The results of the water target test are consistent with the analysis results of the stability of the underwater high-speed rotating projectile with a specific structure.