Numerical Calculation Of Hydrodynamic Characteristics Of Cavitation Flows Around High-speed Projectile

With the rapid development of underwater weapons,there is urgent need to improve the speed of them.The hydrodynamic problem associated with this has become a central issue.Supercavitating occurs when high-speed weapons travel underwater with a 90%decrease in resistance and underwater high-speed supercavitating projectiles have become the focus of national defense research.A generic numerical simulation method is developed to investigate the characteristics of cavity flow around high-speed projectiles traveling in a large range of Mach number.Cavitation models are investigated to better predict the cavity flow in different speed range.In order to make a single cavitation model adjust to a large range of Mach number,a modified Zwart-Gerber-Belamri cavitation model is proposed.It is known that the compressibility of water being a huge effect in transonic and supersonic,the equation of state in water is added to predict the density change.A generic numerical simulation method is developed and several experimental results are calculated to verify the reliability of the method.The calculation results meets well to the experimental phenomenon which illustrates that the numerical simulation method adjusts well in a large range of Mach number.Cavitation flows in a large range of Mach number are investigated by numerical simulation.The characteristics of the cavitation flows are investigated.According the analyze of cavitation flows in different range of Mach number,the cavity width curve is separated with four quadrants in a paragraph.The cavitation flow structure and the resistance of high-speed projectiles are investigated by the paragraph.It is concluded that projectiles behave good stabilities in the first region,slightly worse in the second region and worst in the other part.Cavitator is generally used to improve the cavity quality of high-speed projectiles.The effects of diameters and shape of cavitators in transonic is investigated by numerical simulation.The results show that the increase of diameters of cavitator improve the cavity width but cause a big increase of resistance cutting down the effective route of the projectile.In order to get a benefit of cavity width in transonic and get a tolerable resistance,three shapes of cavitator are investigated.The calculate results show that the cone cavitator with a flat head can improve the cavity width obviously and improve the reliable travel route largely in transonic.It is suggested that a projectile with the cone cavitator with a flat head have a better behavior in transonic flows.