Numerical investigation on the trajectory stability by asymmetric shape effects for water-entry projectiles.

This article investigates the influence of asymmetric nose shapes on the trajectory stability of projectiles entering water at small impact angles, a key factor for safe and stable ocean exploration operations. Using numerical simulations based on the unsteady Reynolds-averaged Navier–Stokes (uRANS) equations, the shear stress transport (SST) k-ω turbulence model, and the volume-of-fluid (VOF) technique, the study finds that a 25% asymmetric ratio—defined by the downward deflection of the projectile's nose tip—significantly improves trajectory stability by balancing pressure distribution on both sides of the nose and reducing attitude angle deflection by 89.97% compared to symmetric shapes. The research also shows that projectiles with this asymmetric ratio produce smaller cavity volumes and simpler wake vortex structures, contributing to reduced oscillations and more stable motion. The findings highlight the importance of nose shape design in controlling hydrodynamic forces during water entry and suggest that adaptive nose shapes could further enhance stability under varying conditions.