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The purpose of this study is to analyze the subsonic and transonic water entry of the axisymmetric body with compressibility effect considered. The water-entry processes of axisymmetric body are numerically investigated, with Tait state equation and energy equation used to describe the compressibility of the liquid. Reasonable agreement has been obtained between the numerical results and the experimental measurements of trajectory, velocity and acceleration. The cavity evolution and dynamic characteristics of subsonic cases are investigated for vertical and oblique water-entry. The results show that the maximum drag coefficient of the oblique water entry is lower, and it is affected by a large moment which causes pitch angle and trajectory inclination angle to change significantly. In the oblique transonic conditions, the effect of compressibility of the liquid on the dynamic flow characteristics is analyzed. On this basis, the influence of entry angle on the hydrodynamic characteristics is investigated. It is concluded that the water-entry angle has a more significant influence on the trajectory characteristics. • Investigate the flow structure and dynamic characteristics of subsonic water-entry cases for vertical and oblique water-entry. • Analyze the effect of compressibility of the liquid on the dynamic flow characteristics of transonic water-entry cases. • Improve the understanding of the influence of entry angle on the hydrodynamic characteristics with compressibility considered. [ABSTRACT FROM AUTHOR]

The objective of this paper is to address the simulation of supercavitating flows around a slender body projectile at the sub-, trans- and supersonic speeds with the water compressibility effects considered. Based on the slender body theory (SBT) and the matched asymptotic expansion method (MAEM), the integro-differential equations for the cases of M a <1 and M a >1 are derived and solved. The results show that there is a good agreement of the supercavity shape for both the cases of M a <1 and M a >1 between the numerical simulation and the experimental results. The influence of Mach number on the supercavity length L , maximum radius R , slenderness λ , the corresponding growth rate of the supercavity length L ˜ , the growth rate of the maximum supercavity radius R ˜ , and the position of the supercavity maximum section (PSMS) are discussed. It can be found that L ˜ is much bigger than R ˜ , due to the large λ . It also concludes that the front part of the supercavity is thicker than the rear part, and the PSMS moves forward further at supersonic speed. Finally, the reason for the supercavity shape transition around M a = 1 is illustrated and it may be the c a use of the extension of perturbation zones at transonic speed. [ABSTRACT FROM AUTHOR]