Comparison of High-Speed Water Entry Movement Process of Axisymmetric Bodies with Different Head Shapes

Abstract

High-speed water entry of the trans-medium axisymmetric body is an instantaneous flow process, involving the complex multiphase flow of the axisymmetric body with the gas and liquid phases. In this paper, a numerical model of cavity dynamics after water entry was established based on Reynolds-averaged Navier-Stokes equations and a multiphase flow model of natural cavitation. The movement characteristics and hydrodynamic force effects of axisymmetric bodies with different head shapes during vertical water entry were studied. The effectiveness of the model and the numerical method was verified by comparing the numerical simulation results with the experimental results in related literature. The results show that the cavity characteristics and the movement speed laws of axisymmetric bodies with different head shapes after water entry are highly different. The corresponding transient drag coefficients also show great differences. The re-entrant jet effect is evident before the cavity is closed, and it affects the cavity shape and resistance of the axisymmetric body. The water entry speed of the axisymmetric body has a direct impact on the cavity size and impact load. When the water entry speed is small, the speed of the axisymmetric body decays relatively faster, and its drag coefficient is relatively larger.

Keywords

• trans-medium axisymmetric body
• water entry
• cavity
• multiphase flow