Hydrodynamic Experimental Research on Launch and Underwater Movement of Projectile

Abstract

This study uses a scaled-down model within a proprietary launch tank to address hydrodynamic complexity post-underwater launch. The model addresses the projectile’s motion characteristics and flow field during ejection. This exploration encompassed varying ejection pressures, motion characteristics of the launch platform, initial ejection angles, and depths of ejection.The results show that the projectile’s residual gas appears as filamentous wake bubbles after underwater ejection, stagnant gas near the tube exit, and bubbles accompanying the projectile. Higher ejection pressure leads to an increase in the volume of stagnant gas at the tube exit, exacerbating the detachment of bubbles accompanying the projectile. When the velocities of the launch platform are V₀ = 0.25 m/s, 0.43 m/s, and 0.48 m/s, the relative attitude angle changes during the projectile’s water-exit are 8.60°, 10.69°, and 16.67°, respectively. The bubbles detach more strongly and shrink in size when the projectile is launched with a particular deflection angle. The volume of stagnant gas at the tube exit and bubbles accompanying the projectile notably diminishes as water depth rises under the same ejection pressure.