Multiphase Flow Field and Motion Stability of Two Spinning Projectiles during Underwater Salvo

The evolution mechanisms of complex multiphase flow field and motion stability of two spinning projectiles during the simultaneous water-exit are investigated. A refined numerical method for cavitation flow interference in simultaneous water-exit is established based on the improved detached eddy simulation (DES) model, a multifunctional decompressed underwater simultaneous launching experimental test system is designed, and the physical parameters involved in the underwater simultaneous launching process are initially summarized and analyzed. The results show that the condition for shedding the cavity attached to the shoulder of spinning projectile is that the moment when the return jet reaches the leading edge of cavity is earlier than the moment when the nose of spinning projectile contacts the water surface. During the water-exit stage, the cavity shrinks to an isolated cavity and undergoes synchronous collapse at the late collapse stage, where the action point of the maximum collapse load is near the end of the cavitary. Although both the free wake vortex structure and the wall vortex structure are the turbulent vortex structures represented by hairpin vortices, they have essential differences. The free wake vortex structure is mainly formed by the rotation of the bottom edge of spinning projectile to generate a vortex ring, while the wall vortex structure is mainly formed by the gradual movement and accumulation of the vortex flow along the surface of spinning projectile. When the lateral spacing is 5 times the diameter of spinning projectile, the morphology and motion attitude of cavity are basically symmetric during the simultaneous water-exit stage, but the interaction of flow fields still persists.