头部非对称运动体倾斜入水实验分析

Experimental analysis on oblique water-entry of asymmetric-headed moving bodies

关键词:  非对称头部  入水实验  入水方式  空泡  多相流

Key words:  asymmetric head  water-entry experiment  water-entry mechanism  cavity  multiphase flow

摘要:

为探究非对称结构倾斜入水过程空泡形态演化与弹道特性,针对不同非对称头型运动体入水开展实验研究。文中使用高速摄像技术对头部非对称运动体入水过程空泡演化与弹体位置进行记录。基于数字图像处理技术,提取不同头型非对称运动体的运动轨迹及姿态,对比分析头部形状与入水方式对入水空泡演化与弹道特性的影响。研究结果表明:头部非对称运动体入水空泡演化具有2次开空泡、2次喷溅、1次空泡附着、空泡融合、2次空泡溃灭等独特的空泡流动特性；运动体头部形状会严重影响入水空泡的演化和弹道特性；随着运动体头型从凸头形状向凹头形状转变,喷溅水幕的宽度、空泡的大小以及运动体的姿态角会逐渐增大。相反,2次空泡的闭合时间却逐渐减小。此外,当头部非对称运动体以反向方式入水时,其更易达到水平运动状态,运动体入水后达到水平运动状态的时间大幅减小,这一特性对实际工程应用具有指导意义。

Abstract:

To explore the cavity evolution and ballistic characteristics during the oblique water-entry of asymmetric structures, experimental research was conducted on various asymmetric-headed bodies. High-speed imaging technique was utilized to capture the cavity evolution and body position during the water-entry process of asymmetric-headed moving bodies. Utilizing digital image processing, trajectories and attitudes of these bodies were extracted. A comparative analysis was then performed to assess the impact of head shape and entry mode on cavity evolution and ballistic characteristics. The results show that the evolution of the water entry cavity of asymmetric-headed moving bodies has unique cavity flow characteristics such as secondary open cavity, secondary splashing, primary cavity attachment, cavity fusion, and secondary cavity collapse. The shape of the head of the moving body will seriously affect the evolution of the water-entry cavity and the ballistic characteristics of the moving body. As the shape of the head of the moving body changes from a convex shape to a concave shape, the width of the splash water curtain, the size of the cavity curtain, the size of the cavity and the attitude angle of the moving body will gradually increase. On the contrary, the closure time of the secondary cavity will gradually decrease. This characteristic has a profound impact on practical engineering applications.