High-speed water entry triggers free liquid surface breakup, vacuole generation, shock wave propagation and structural loading in a very short time, and the water entry attitude, rotation, multiple bomb interferences, and active jets all change the vacuole closure position and loading path. In this paper, a parametric computational framework combining gas-liquid two-phase interface capture, six-degree-of-freedom motion and structural flexible feedback is established around the high-speed water entry process of transmedia navigation body, and four typical working conditions, namely, rotation-induced asymmetric vacuole, air-jet-assisted disc-head entry, multi-bullet parallel vacuole interference, and super-vacuole tail slap collision, are included in the unified analysis. The results show that when the water entry angle is increased from 0° to 15°, the air bubble axial offset is increased from 0.02D to 0.58D, and the peak lateral moment is increased by about 3.7 times; when the velocity ratio is more than 3.0 and the flexibility parameter is higher than 0.35, the tail slap risk index enters into the interval of 0.70 or more. After the air-jet flow coefficient reaches 0.04, the peak load can be reduced by about 35.6%, and the gain tends to slow down when the jet strength continues to increase. The study illustrates that high-velocity entry stability cannot be determined by head shape or a single velocity parameter alone, but must simultaneously consider free surface boundaries, air bubble closure, structural flexibility, and control response delay.
