Analysis of Entry Load and Motion Response of High-Pressure Escape Chamber with Airbag Under Wave Condition

To reduce impact loads during the water entry of a high-pressure escape capsule into waves, this study equips its bottom with a cushioning airbag. A numerical model is developed for the water-entry impact of this airbag-equipped capsule. This model couples the arbitrary Lagrangian–Eulerian (ALE) method with a piston-type wave-generation method, while the airbag’s behavior is captured using the control-volume (CV) method. Numerical simulations and model tests are performed for a hollow wedge block entering water. The numerical approach is validated by comparing the computed acceleration and deformation shapes with experimental measurements. Further numerical simulations are then conducted to analyze the impact loads and motion responses of the airbag-equipped capsule under regular waves. The investigation focuses on the effects of airbag shape, initial entry velocity, entry angle, and wave conditions. The results show that a raft-shaped airbag effectively reduces impact loads and promotes an earlier rebound of the capsule to the water surface. As the entry angle increases, the vertical acceleration first declines and then rises, while the airbag’s buffering effect is weakened and delayed. Moreover, the peak values of vertical acceleration, displacement, and internal airbag pressure under wave conditions are all greater than those in still water. This difference becomes more significant at lower entry velocities.