Effects of Lateral Flows on the Supercavitation and Hydrodynamic Characteristics of Underwater Series and Parallel High-Speed Projectiles

Abstract

In this paper, the supercavitation of the parallel and tandem projectiles moving underwater with high-speed under the condition with/without lateral flows is numerically simulated by the volume of fraction (VOF) model. The motion of the projectiles was handled by the overlapping grid and six degrees of freedom (DOF) techniques. The supercavitation evolution and the hydrodynamic characteristics of the projectiles were analyzed for the parallel and tandem projectiles under different conditions. The results show that the cavity shape is symmetrical under the condition without lateral flows, but is no longer symmetrical under the conditions with lateral flows. The asymmetry of the cavity contour increases with the velocity of the lateral flow. For the parallel projectiles, the change trends of the axial velocity of projectile 1 and projectile 2 are nearly the same. The offset velocity of projectile 1 and projectile 2 increases with the increase in the velocity of the lateral flow. The deflection angle of projectile 1 decreases with the increase in the lateral flow velocity but that of projectile 2 increases with the increase in the lateral flow velocity. At t = 3.0 ms, the deflection angle of projectile 2 is up to 20° under the condition of the lateral flow velocity of 11.25%, while the deflection angle of projectile 1 and 2 under other conditions is in the range of 5°. For the tandem projectiles, the axial velocity of projectile 1 gradually decreases. The change trend of the axial velocity of projectile 2 at first is the same as that of projectile 1, and then the change is dependent on the velocity of the lateral flow. Under the condition of the lateral flow velocity with 11.25%Vp, projectile 2 cannot enter the cavity of the front projectile. The change trend of the axial velocity of projectile 2 is similar as but somewhat slower than that of projectile 1. For the parallel projectiles, the ballistic stability of the projectile on the oncoming side is better than that of the projectile on the backflow side. Whether parallel or tandem projectiles, the ballistic stability of projectile 2 becomes worse with the increase in the lateral flow velocity.

Influence of Periodic Disturbance Incoming Flow on the Supercavitation Phenomenon

“…Wang et al studied the influence of periodic gust flow on the cavitation shape at the tail of ventilated supercavitation . Zhan et al studied the influence of lateral flow on supercavitation and concluded that the cavity morphology is symmetrical in the absence of lateral flow and asymmetrical in the presence of lateral flow, with the cavity morphology increasing with the velocity . Fan et al studied the change in supercavitation when the projectile passes through different density regions and found that the diameter contraction of the projectile occurs through different density regions and in different locations and is related to the density degree .…”

“… 17 Zhan et al studied the influence of lateral flow on supercavitation and concluded that the cavity morphology is symmetrical in the absence of lateral flow and asymmetrical in the presence of lateral flow, with the cavity morphology increasing with the velocity. 18 Fan et al studied the change in supercavitation when the projectile passes through different density regions and found that the diameter contraction of the projectile occurs through different density regions and in different locations and is related to the density degree. 19 Zhan et al studied the influence of different wave phases and heights on the supercavitation flow field and found that the wave phases and height affect the resistance of supercavitation.…”