Focused on cavity dynamics in high Froude number (10<Fr<40) water entry for projectiles, the vertical water entry experiments of conical, hemispherical and flat-nose projectiles are carried out. The image data is obtained by using a high-speed video camera and post-processing software. The cavity dynamics in the transition process from surface seal not occurring to surface seal occurring are studied. Then the effects of Froude number and Cavitation number on the surface seal time, deep seal time, depth of deep seal and the maximum radius of the cavity on water surface and at the depth of deep seal are analyzed. The results show that in the range of Froude number from 10 to 40, for the flat nose, the trend of the surface seal time is piecewise as the Froude number increases due to the influence of the projectile tail. For the hemispherical nose, the critical Froude number of whether the surface seal occurs is about 22, and the value of the conical nose is about 24. After the surface seal occurs, with the increase of the Froude number, the maximum radius of the cavity at the water surface of flat and hemispherical noses decreases, while the maximum radius of the conical nose slowly increases under the influence of the moderate jet. Besides, after the surface seal occurs, the depth of deep seal for the hemispherical nose increases slowly first and then decreases, while the depth for the conical nose increases slowly.

专注于高弗洛德数（10 < Fr<40）射弹的入水，进行了锥形，半球形和扁鼻射弹的垂直入水实验。图像数据是通过使用高速摄像机和后处理软件获得的。研究了从未发生表面密封到发生表面密封的过渡过程中的腔动力学。然后分析了弗洛德数和空化数对水面封闭时间，深层封闭时间，深层封闭深度以及水面和深层封闭深度处空腔最大半径的影响。结果表明，在弗劳德数从10到40的范围内，对于扁鼻子，由于炮弹尾部的影响弗劳德数增加，表面密封时间呈分段变化的趋势。对于半球形的鼻子，是否发生表面密封的临界弗洛德数约为22，圆锥形鼻的值约为24。发生表面密封之后，随着弗洛德数的增加，水在水表面的最大半径在中等射流的影响下，扁平鼻和半球形鼻逐渐减小，而锥形鼻的最大半径逐渐增大。此外，在发生表面密封之后，半球形鼻的深密封深度先缓慢增加然后减小，而锥形鼻的深度则缓慢增加。锥形鼻的最大半径在中等射流的影响下缓慢增加。此外，在发生表面密封之后，半球形鼻的深密封深度先缓慢增加然后减小，而锥形鼻的深度则缓慢增加。锥形鼻的最大半径在中等射流的影响下缓慢增加。此外，在发生表面密封之后，半球形鼻的深密封深度先缓慢增加然后减小，而锥形鼻的深度则缓慢增加。