Dynamic analysis in polar exploration: Fluid-structure interaction modeling of projectile colliding with floating ice during water entry

In polar resource exploration, the interaction between polar detectors and floating ice, as well as their water entry mechanisms, are crucial for ensuring effective detector operation and data collection. This study developed a fluid-structure interaction (FSI) model to simulate the water entry of the projectile in a multidegree motion state upon collision with the floating ice, and the numerical method was validated through experiments. This study analyzes the mechanisms of cavity evolution and the laws of cavity pinch-off. This analysis further explores the motion states and dynamic characteristics under the interaction between the projectile and the floating ice. Additionally, this study also considers the influence of structural parameters of the floating ice, including thickness (L_t), width (L_w), and collision position (S_d), on the water entry process. The study reveals that increasing the submergence depth of the floating ice enhances the stability between the floating ice and water, and can mitigate flow separation phenomena generated by passive motion under inertial effects. Variations in the floating ice thickness significantly affect the cavity evolution and the projectile's underwater motion state. Conversely, variations in the floating ice width notably affect the liquid level disturbances, the development of splash crowns, and the evolution of passive water entry cavities. In specific multidegree motion states, various collision positions do not alter the evolution form of water entry cavities, yet the variation in collision positions notably affects floating ice displacement. As the collision position shifts from the center to the side edge of the floating ice, both the hydrodynamic forces on the projectile and the stress on the floating ice gradually decrease, with the decrease in hydrodynamic forces being the most significant, reaching up to 58%. This study is important for enhancing multi-body fluid-structure interaction algorithms and advancing polar exploration engineering development.