Dynamics analysis of deflated cylindrical shell during high-speed water entry

This paper uses a bidirectional fluid structure interaction numerical simulation method to research high-speed vertical water entry of the deflated cylindrical shell, and compares and analyzes the cavity evolution, motion characteristics, and structural deformation characteristics with semi-sealed, completely opened, and completely sealed cylindrical shells, comprehensively analyzing the unique physics mechanism of deflated cylindrical shells. The results indicate that the semi-sealed cylindrical shell generates a downward jet during high-speed water entry, while a clear jet is generated at the middle hole position of the completely opened cylindrical shell. The cavity formed by the deflated cylindrical shell simultaneously has a downward jet and a through hole jet in the middle position. Because of its more complex internal fluid flow, it is more susceptible to disturbances during high-speed water entry. As the diameter of the hole increases, the cavity evolution and motion characteristics of the deflated cylindrical shell become closer to those of a completely opened cylindrical shell. As the diameter of the hole decreases, the cavity evolution and motion characteristics of the deflated cylindrical shell become closer to those of a semi-sealed cylindrical shell.