TITLE:
Vertical Water-Entry of Bullet-Shaped Projectiles
AUTHORS:
Erren Yao, Huanran Wang, Long Pan, Xinbing Wang, Rihai Woding
KEYWORDS:
Vertical Water-Entry, Cavity, Pressure Difference, Cylindrical Projectile
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.2 No.6,
May
16,
2014
ABSTRACT: The vertical water-entry behavior of bullet-shaped
projectiles was experimentally and theoretically studied. Particular
attention was given to characterizing projectile dynamics, the resultant
evolution of air cavity and particularly surface closure before deep closure in
the moderate speed. We developed equations for the projectile motion with
significant and negligible gravitational effects. Based on the solution to the
Rayleigh-Besant problem, a theoretical model was developed to describe the
evolution of the cavity shape, including the time evolution of the cavity on
fixed locations and its location evolutions at fixed times. The gravitation
effects during the initial stage of the impact of the projectile on the water
can be ignored, but those during the later stage should be considered, many
literatures do not have the report of this aspect. The theoretical predictions
were consistent with the experimental observations. The evolution of air cavity
had a significant effect on ballistic stability.