Influence Rule of Projectile Density on the Characteristics of High-Speed Water-Entry Cavity

Document Type : Regular Article


1 School of Mechanical Engineering and Automation, Northeastern University, Shenyang110819, China

2 School of Control Engineering, Northeastern University at Qinhuangdao, Qinhuangdao066004, China

3 Heilongjiang North Tool Co., Ltd, Mudanjiang157000, China



There has been much recent research on high-speed projectiles entering water, but research on the selection of the material for supercavitating projectiles is limited. Some important properties of such projectiles—mass and moment of inertia, for example—are related to the material density, so the projectile’s density has an important effect on the performance of the supercavitating projectile. This study, using Ansys fluent 19.0 simulation software, studied the details of water entry of four high-speed projectiles of the same shape but made of different materials: aluminum (2.7 g/cm3), steel (7.85 g/cm3), brass (8.5 g/cm3), and tungsten alloy (17.5 g/cm3). The cavity shape, ballistic and hydrodynamic characteristics, and cavity flow field characteristics of projectiles with different densities were analyzed for a water-entry velocity of 600 m/s. The results show that within 3 ms, the velocity of a projectile with a density of 2.7 g/cm3 drops to 171.8 m/s, and the velocity of a projectile with a density of 17.5 g/cm3 drops to 433.1 m/s. Increasing the density of the projectile evidently reduces the deceleration of the projectile. The drag coefficient depends, primarily on the size and shape of the projectile, only slightly on its density. Just after water-entry time, the higher the density of the projectile, the faster the expansion of its cavity wall. As time after water entry increases, the expansion velocity of the cavity wall gradually decreases. The simulation results show that the projectile head experiences the greatest pressure, producing a sharp peak, at the moment when it touches the water surface. During the flow stabilization phase, the lower the density of the projectile, the lower the pressure on the head of the projectile. The results of this study will help to guide the selection of material for supercavitating projectiles.


Akbari, M. A., J. Mohammadi and J. Fereidooni (2021). Stability of oblique water entry of cylindrical projectiles. Journal of Applied Fluid Mechanics 14(1), 301-314.##
Aristoff, J. M. and J. W. M. Bush (2009). Water entry of small hydrophobic spheres. Journal of Fluid Mechanics 619,45-78.##
Aristoff, J. M., T. T. Truscott, A. H. Techet and J. W. M. Bush (2010). The water entry of decelerating spheres. Physics of Fluids 625,135-165.##
Bodily, K. G.,S. J. Carlson and T. T. Truscott (2014). The water entry of slender axisymmetric bodies. Physics of Fluids 26(7), 45-78.##
Choi, J. H., R. C. Penmetsa and R. V. Grandhi (2005). Shape optimization of the cavitator for a supercavitating torpedo. Structural and Multidisciplinary Optimization 29(2), 159-167.##
Fan, C. Y., Z. L. Li, B. C. Khoo and M. C. Du (2019). Supercavitation phenomenon research of projectiles passing through density change area.    Aip Advances 9(4).##
Forouzani, H., B. Saranjam and R. Kamali (2018). A study on the motion of high-speed supercavitating projectiles. Journal of Applied Fluid Mechanics 11(6), 1727-1738.##
Gao, J. G., Z. H. Chen, Z. G. Huang, W. T. Wu and Y. J. Xiao (2019). Numerical investigations on the oblique water entry of high-speed projectiles. Applied Mathematics and Computation 362.##
Gaudet, S (1998). Numerical simulation of circular disks entering the free surface of a fluid. Physics of Fluids 10(10), 2489-2499.##
Gilbarg, D. and R. A. Anderson (1948). Influence of atmospheric pressure on the phenomena accompanying the entry of spheres into water. Journal of Applied Physics 19(2), 127-139.##
Guo, Z. T (2012). Research on characteristics of projectile water entry and ballistic resistance of targets under different mediums. Ph. D. thesis, Harbin Institute of Technology, Harbin, China.##
Jafarian, A. and A. Pishevar (2016). Numerical Simulation of Steady Supercavitating Flows. Journal of Applied Fluid Mechanics 9(6), 2981-2992.##
Lee, M., R. G. Longoria and D. E. Wilson (1997) . Cavity dynamics in high-speed water entry. Physics of Fluids 9(03), 540-550.##
Logvinovich, G. V. (1973). Hydrodynamics of flows with free boundaries. Halsted Press.##
May, A. (1952). Vertical entry of missiles into water. Journal of Applied Physics 23(12), 1362-1372.##
Meng, Q. C., W. B. Yi., M. Y. Hu., Z. H. Zhang and J. B. Liu (2019). Study on Cavity Profile and Hydrodynamics of High-speed Vertical Water Entry of Projectile. Shipbuilding of China 60(03),12-26.##
Menter, F. R., M. Kuntz and R. Langtry (2003). Ten years of industrial experience with the SST turbulence model. Turbulence Heat & Mass Transfer 4, 625-632.##
Nair, V. V. and S. K. Bhattacharyya (2018). Water entry and exit of axisymmetric bodies by CFD approach. Journal of Ocean Engineering and Science 3(2),156-174.##
Schnerr, G. H. and J. Sauer (2001). Physical and numerical modeling of unsteady cavitation dynamics. Fourth International Conference on Multiphase Flow (Vol. 1).##
Shang, Z (2013). Numerical investigations of supercavitation around blunt bodies of submarine shape. Applied Mathematical Modelling 37(20-21), 8836-8845.##
Shi, Y., G. H. Wang and G. Pan (2019). Experimental study on cavity dynamics of projectile water entry with different physical parameters. Physics of Fluids 31(6).##
Sorensen, B. R., K. D. Kimsey and B. M. Love (2008). High-velocity impact of low-density projectiles on structural aluminum armor. International Journal of Impact Engineering 35(12), 1808-1815.##
Wang, X. F., J. B. Liu, B. Wu, D. F. Kong, J. R.  Huang, X. Y. Xu and X. Bao (2020). Cratering for Impact of Hypervelocity Projectiles into Granite Targets within a Velocity Range of 1.91-3.99 km/s: Experiments and Analysis. Applied Sciences-Basel, 10(4).##
Yao, E. R., H. R. Wang, L. Pan, X. B. Wang and R. H. Woding (2014). Vertical water-entry of bullet-shaped projectiles. Journal of Applied Mathematics and Physics (2), 323-334.##
Zhang, H., H. F. Wang, Q. B. Yu, Y. F. Zheng, G. C. Lu and C. Ge (2021). Perforation of double-spaced aluminum plates by reactive projectiles with different densities. Materials 14(5).##
Volume 15, Issue 6 - Serial Number 67
November and December 2022
Pages 1901-1912
  • Received: 15 May 2022
  • Revised: 07 July 2022
  • Accepted: 05 August 2022
  • Available online: 07 September 2022