Cavitation dynamics of the semi-sealed cylindrical shell during high-speed water entry

Abstract

This paper experimentally investigates the vertical high-speed water entry of a semi-sealed cylindrical shell, which has one end sealed and one end opened. The unsteady water-entry cavitating flow characteristics of the shell are analyzed, and the evolution of cavities and jet impacts with different structures is studied. The results show that a nested multi-cavity is generated due to the self-jet phenomenon during water entry. The jet causes the diameter of the secondary cavity to be much larger than that of the primary cavity, and the morphology of the secondary cavity is more atomized. Due to the irregular motion of the jet, the primary cavity undergoes neck-shrinking phenomenon and is compressed, and the neck-shrinking position moves up as the secondary cavity grows. After secondary impact, a small jet appears at the bottom of the shell, which ejects out from the shell and increases the size of the bottom cavity, leading to the formation of quaternary cavity. Moreover, as the inner wall length increases, the time of the primary jet is advanced, while the depth of secondary cavity shortens. With the increase in the thickness, cavity shape becomes more similar to traditional supercavity, and the maximum diameter of the primary cavity increases.