Experimental investigation of bounce phenomenon

During the entry of objects into water, several fluid dynamics phenomena, such as air and vapor cavities and jet formation, occur that contribute to the bouncing behavior of the body. In this study, experimental tests are carried out to investigate these effects. In these tests, the consequences of speed and entry angle changes along with different model nose shapes, on bounce phenomenon, are explored. Two models, with different lengths, including hemispherical and conical nose shapes, are also designed, prepared and tested in a test tank, equipped with a high speed movie camera and launching system. As the muzzle velocity increases and the water entry angle decreases, it is observed that the hemispherical nose model has no essential orientation change, while the conical nose model bears an orientation change that is quite large and which may end up in the bounce of the model. This is mainly related to the extent of the separation and jet formation on the nose surface, which is discussed in this paper. A numerical model of the experiment also predicts the same behavior.