Numerical research of high-speed oblique water-entry of projectile based on rigid body and fluid-structure interaction model

Abstract

When a projectile enters the water at high speed, the projectile can suffer a huge impact of water. If a deformation occurs in the structure of the projectile during water-entry, the numerical method based on rigid body model will be limited, while the accuracy and precision of the results can be affected. The two numerical methods of the rigid body and fluid-structure interaction (FSI) model have been built to get the results of the oblique water-entry of the projectile in this paper. Moreover, the numerical results for the given projectile under the same water-entry conditions (initial angle of incidence of θ = 15°, initial angle of attack of α = 5°, initial speed of V = 200m/s ) have been contrasted. The results show that if a small deformation occurs in the body of the projectile during the water-entry, the numerical results of the FSI and the rigid body are different. Further, the small deformation within the limit of flexibility can change the motion attitude and the trajectory of projectile during the water-entry, meanwhile the change can cause the bending of the ballistic and the super-cavity. For the projectile with the structural response, the change in the distribution of the stress concentration area can affect the drag force suffered by projectile.