高速射弹并联入水过程空泡演化特性试验

为研究多射弹并联入水时多空泡演化特征,首先设计了可用于双射弹水平高速入水的发射装置,通过试验验证了该系统的可行性；然后基于该系统进行了不同空化器直径、径向间距的双射弹并联入水试验,利用高速摄影技术采集到双射弹在并联入水运动过程；最后对采集到的运动序列图片进行数据分析,得到双射弹在并联入水过程中的双空泡演化规律,揭示了射弹并联入水过程中空泡之间的耦合演化机理. 试验结果表明: 高速射弹并联入水过程中,其空泡演化过程存在穿越、吸引及截断3种典型现象；空化器直径与射弹径向间距均是影响双空泡耦合特性的重要因素.相同射弹径向间距时,随着射弹空化器直径减小,双空泡之间的耦合程度减弱,完全穿越转变成部分穿越现象；相同的空化器直径时,随着双射弹的径间距增大,射弹的脱落空泡之间的吸引现象逐渐减弱,但是脱落空泡的偏移幅值随着径向间距的增大呈现先增大后减小的变化趋势；当双射弹存在前后距离时,先发射弹易出现空泡的截断现象.随着轴向间距增大,截断现象将减弱.根据独立膨胀原理可知,相同条件下射弹前后间距减小时截断现象亦将减弱.

Experimental study on cavitation evolution of high-speed projectile water entry in parallel

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.