Ricochet behavior of air–water trans-media vehicle during water-entry crossing

Abstract

In this study, the ricochet behavior of air–water trans-media vehicle (AWTMV) during water-entry crossing was evaluated by both theoretical computations and experiments. First, Logvinovich model was introduced to predict the shape of cavitation. The AWTMV was divided into three areas to deduce hydrodynamic forces based on the relative position of AWTMV and cavitation. Accordingly, a mathematical model of AWTMV during water-entry crossing was established. Then, three types of projectiles including the nose of cone, ogive, and flat were used on an angle-adjustable experimental system to analyze the ricochet behavior under different initial conditions. A comparative analysis was carried out to evaluate the influence on trajectory. The computational and experimental results show a good agreement. Further, the effect of noses on ricochet behavior was evaluated; the experimental and calculation results show that the AWTMV with a cone nose is more likely to change trajectory and behavior under the same initial conditions. Finally, the critical angles of ricochet were derived based on the mathematical model, and an empirical formula is proposed to predict the occurrence of ricochet behavior. These results provide a reference for the design and use of AWTMV.