The influence of thin-wall slope on the high-speed water entry of a semi-sealed cylindrical shell

The Star-CCM+and ABAQUS co-simulation method is used to conduct fluid structure interaction research on high-speed water entry of shells with different slopes in this paper. The results indicate that the slope of the shell has a significant effect on the cavity evolution, motion characteristics, and structural response of the shell. The cross-section of the secondary cavity generated by a shell with a larger slope angle are closer to a circular shape, and the fluid inside will generate downward thrust when it gushes out, resulting in a greater velocity and displacement of the shell. The shell with inward inflection point position has a smaller velocity and displacement. After the conical and hemispherical shells penetrate into the water, their velocity decays extremely fast. The position of the shell is always close to the height of the free surface, and there is also a phenomenon of upward floating of the hemispherical shell due to its velocity decreasing to a negative value. The cavity generated by the conical shell are similar to the shape of a gourd, while the hemispherical shell only forms smaller secondary cavity at the lower position, which are significantly smaller in volume compared to the primary cavity.