After the outer shell of the double-shell submarine is damaged by the near-field underwater explosion shock wave, the subsequent bubble pulsation and jet load will continue to cause serious damage to the inner shell of the submarine. Therefore, it is of great significance to study the characteristics of bubble pulsation and bubble load near the hole. Based on the double-shell submarine structure damaged by the shock wave, a double-layer cylindrical structure model with a prefabricated circular hole is made. Using an electric spark device as the bubble generator, the interaction experiments between bubbles and double-layer cylindrical structure with a hole under different explosion distance parameters (the ratio of explosion distance to the maximum diameter of bubbles) and different hole parameters (the ratio of hole diameter to the maximum diameter of bubbles) are carried out. A high-speed camera is used to capture the bubble pulsation and jet formation process near the double-layer cylindrical structure. The particle image velocimetry technology is used to test the velocity of the explosion flow field to obtain the jet velocity after the bubble collapse. At the same time, a pressure sensor is used to measure the pressure load on the inner cylindrical shell wall. The experimental results show that the detonation distance parameters determine the form of pressure load on the inner wall, whether effective jet is generated after the bubble collapse, and the jet velocity. When the detonation distance parameters are within a certain range, the hole parameters will affect the bubble pulsation and the direction of the water jet generated after the bubble collapse.

Contact explosion is an important condition in the damage and protection of underwater structures, and the pulsating bubbles generated by explosive underwater explosion are an important damage source. The current research on underwater explosion bubbles mainly focuses on the pulsating characteristics of spherical bubbles under free-field and typical boundary conditions, while there is a notable lack of research on non-spherical bubbles under contact explosion conditions. The pulsation characteristics of underwater contact explosion bubbles were systematically investigated through theoretical modeling, numerical simulations, and experiments. To address the theoretical gap in contact explosion dynamics, a hemispherical bubble dynamics model under rigid wall contact conditions was established based on incompressible and inviscid fluid assumptions. By comparing present model with the spherical bubble pulsation model in an incompressible flow field, quantitative relationships between parameters such as the maximum bubble radius, initial radius, pulsation period were obtained. Theoretical analysis reveals that the maximum radius, initial radius, and pulsation period of contact explosion bubbles are 1.26 times (theoretical scaling factor) those of free-field conditions. An error analysis was conducted to account for factors such as fluid compressibility, unstable bubble deformation, and energy dissipation induced by bubble-rigid wall interactions. Numerical simulations using LS-DYNA for underwater explosions with 0.300 g, 0.233 g, and 5.000 g TNT charges under varying water depths reveal that the scaling factors for maximum radius and pulsation period under contact explosion conditions range from 1.22 to 1.24 and 1.20 to 1.21 times those of free-field results, respectively, with simulation errors below 5% compared to theoretical predictions. Experimental validation in a water tank shows that the maximum radius and period of contact explosion bubbles are 1.10 and 1.06 times those of free-field conditions. During the experiments, plate vibrations were observed upon explosion, which significantly contributed to experimental errors. This work addresses the theoretical gap in contact explosion bubble dynamics, enhances the understanding of boundary effects in underwater explosion phenomena.