Numerical investigation on the cavitation collapse regime around the submerged vehicles navigating with deceleration

In the present work, the collapse regimes of the cavitation occurring on the submerged vehicles navigating with deceleration were numerically investigated. A homogeneous equilibrium cavitation model was combined with the pressure velocity density coupling algorithm to simulate the cavitating flows. The cavity is induced to collapse by the deceleration after fluctuation, and the first collapse releasing most of the energy is followed by a series of secondary ones. The collapse process can be classified into two types: periodic oscillation and damped oscillation. In each type the evolution of the total mass of vapor in cavity is found to have strict correlation with the pressure oscillation in the far field. The two types are different in the intensity and the bandwidth of the pressure peaks. By defining the equivalent radius of cavity, we introduce the specific kinetic energy of collapse and demonstrate that its change-rate is in good agreement with the pressure disturbance. It is also found that the drag presents corresponding oscillations. Through comparative analysis on the velocity field and the stress distribution along the body, it indicates that the collapse can produce extremely high pressure instantaneously. We numerically investigated the influence of the angle of attack on the collapse regime. The result shows that when the vehicle decelerates, an asymmetric-focusing effect of the pressure induced by collapse occurs on its pressure side. We analytically proved such an asymmetric-focusing effect using the potential flow theory. The mathematical model and method we proposed show capability in reflecting the evolution of the pressure difference between both sides of the vehicle. (C) 2014 Elsevier Masson SAS. All rights reserved.