Abstract:To study the multi-cavity evolution characteristics of parallel multi-projectile water entry, the launcher that can be used for high-speed water entry in parallel was designed, and the feasibility of the system was verified by experiments. Then, based on the system, the test on parallel double-projectile water entry was carried out with different cavitator diameters and radial spacing. The high-speed photographic technology was used to collect the movement process of double-projectile water entry in parallel. Finally, the collected motion sequence images were analyzed to obtain the data of double-projectile water entry in parallel. The evolution law of double cavitation in the process of parallel water entry was obtained, which reveals the coupling evolution mechanism between the cavitation of the projectiles entering water in parallel. Results show that there were three typical phenomena of crossing, attraction, and truncation in the process of cavitation evolution of high-speed projectiles. The cavitator diameter and the radial distance of projectile were important factors affecting the coupling characteristics of double-cavity. When the radial distance of the projectiles was constant, as the diameter of the projectile cavitator decreased, the degree of coupling between the double cavitation was weakened, and the complete crossing phenomenon became a partial crossing phenomenon. Under the same cavitator diameter, with the radial distance increased, the attraction phenomenon between the shedding cavities of the projectiles was gradually weakened, while the offset amplitude of the shedding cavities increased first and then decreased with the increase of the radial distance. When there was a front-to-back distance between the double-projectile, the first projectile was prone to the truncation phenomenon. As the radial distance increased, the truncation diminished. According to the principle of independent expansion, the truncation phenomenon will also be weakened when the distance between the front and back of the projectile was reduced under the same conditions.
