scholarly journals Numerical investigations of trajectory characteristics of a high-speed water-entry projectile

AIP Advances ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 095107
Author(s):  
Qiang Li ◽  
Lin Lu ◽  
Tao Cai
Keyword(s):  
High Speed ◽  
Water Entry ◽  
Numerical Investigations

Numerical investigations on the oblique water entry of high-speed projectiles

2019 ◽  
Vol 362 ◽  
pp. 124547
Author(s):  
Jian-Guo Gao ◽  
Zhi-Hua Chen ◽  
Zhen-Gui Huang ◽  
Wei-Tao Wu ◽  
Yu-Jie Xiao
Keyword(s):  
High Speed ◽  
Water Entry ◽  
Numerical Investigations

scholarly journals Numerical Investigations of Cavitation Nose Structure of a High-Speed Projectile Impact on Water-Entry Characteristics

2020 ◽  
Vol 8 (4) ◽  
pp. 265
Author(s):  
Qiang Li ◽  
Lin Lu
Keyword(s):  
Drag Reduction ◽  
High Speed ◽  
Flow Characteristics ◽  
Water Entry ◽  
Navier Stokes ◽  
Cavitation Model ◽  
Lower Velocity ◽  
Numerical Investigations ◽  
Velocity Attenuation ◽  
Trajectory Stability

In this study, a detailed analysis of the influences of cavitation nose structure of a high-speed projectile on the trajectory stability during the water-entry process was investigated numerically. The Zwart-Gerber-Belamri (Z-G-B) cavitation model and the Shear Stress Ttransport (SST)k-ω turbulence model based on the Reynolds Averaged Navier–Stokes (RANS) method were employed. The numerical methodology was validated by comparing the numerical simulation results with the experimental photograph of cavitation shape and the experimental underwater velocity. Based on the numerical methodology, the disk and the conical cavitation noses were selected to investigate the water-entry characteristics. The influences of cavitation nose angle and cavitation nose diameter of the projectile on the trajectory stability and flow characteristics were carried out in detail. The variation features of projectile trajectory, velocity attenuation and drag were conducted, respectively. In addition, the cavitation characteristics of water-entry is presented and analyzed. Results show that the trajectory stability can be improved by increasing the cavitation nose angle, but the drag reduction performance will be reduced simultaneously. Additionally, due to the weakening of drag reduction performance, the lower velocity of the projectile will cause the damage of the cavitation shape and the trajectory instability. Furthermore, the conical cavitation nose has preferable trajectory stability and drag reduction performance than the disk cavitation nose.

Impact Flash at High Speed Water Entry

1951 ◽  
Vol 22 (3) ◽  
pp. 360-361 ◽  
Author(s):  
J. H. McMillen ◽  
R. L. Kramer ◽  
D. E. Allmand
Keyword(s):  
High Speed ◽  
Water Entry ◽  
Impact Flash

Numerical investigations on the deformation styles and stress distributions of hyperelastic/viscoelastic spheres during water entry

2020 ◽  
Vol 127 (6) ◽  
pp. 064901 ◽  
Author(s):  
Liu Yang ◽  
Yingjie Wei ◽  
Cong Wang ◽  
Weixue Xia ◽  
Jiachuan Li
Keyword(s):  
Water Entry ◽  
Stress Distributions ◽  
Numerical Investigations

scholarly journals The Hydrodynamics of High Diving

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 73
Author(s):  
Thibault Guillet ◽  
Mélanie Mouchet ◽  
Jérémy Belayachi ◽  
Sarah Fay ◽  
David Colturi ◽  
...  
Keyword(s):  
Water Surface ◽  
High Speed ◽  
Water Entry ◽  
Air Cavity ◽  
Initial Height

Diving consists of jumping into water from a platform, usually while performing acrobatics. During high diving competitions, the initial height reaches 27 m. From this height, the crossing of the water surface occurs at 85 km/h, and as such it is very technical to avoid injuries. Major risks occur due to the violent impact at the water entry and the formation and collapse of the air cavity around the diver. In this study, we investigate experimentally the dynamics of the jumper underwater and the hydrodynamic causes of injuries in high dives by monitoring dives from different heights with high-speed cameras and accelerometers in order to understand the physics underlying diving.

All-Speed Time-Accurate Underwater Projectile Calculations Using a Preconditioning Algorithm

2005 ◽  
Vol 128 (2) ◽  
pp. 284-296 ◽  
Author(s):  
Michael Dean Neaves ◽  
Jack R. Edwards
Keyword(s):  
High Speed ◽  
Compressible Flows ◽  
Time Derivative ◽  
Water Entry ◽  
Ideal Gas ◽  
Projectile Motion ◽  
Imaging Results ◽  
Underwater Projectile ◽  
Phase Water ◽  
Compressibility Effects

An algorithm based on the combination of time-derivative preconditioning strategies with low-diffusion upwinding methods is developed and applied to multiphase, compressible flows characteristic of underwater projectile motion. Multiphase compressible flows are assumed to be in kinematic and thermodynamic equilibrium and are modeled using a homogeneous mixture formulation. Compressibility effects in liquid-phase water are modeled using a temperature-adjusted Tait equation, and gaseous phases (water vapor and air) are treated as an ideal gas. The algorithm is applied to subsonic and supersonic projectiles in water, general multiphase shock tubes, and a high-speed water entry problem. Low-speed solutions are presented and compared to experimental results for validation. Solutions for high-subsonic and transonic projectile flows are compared to experimental imaging results and theoretical results. Results are also presented for several multiphase shock tube calculations. Finally, calculations are presented for a high-speed axisymmetric supercavitating projectile during the important water entry phase of flight.

Experimentally Measured Hydroelastic Effects on Impact-Induced Loads during Flat Water Entry and Related Uncertainties

2019 ◽  
pp. 1-30
Author(s):  
Simon Toedter ◽  
Ould el Moctar ◽  
Jens Neugebauer ◽  
Thomas E. Schellin
Keyword(s):  
High Speed ◽  
Water Entry ◽  
Test Case ◽  
Primary Concern ◽  
Air Trapping ◽  
Flat Bottom ◽  
Benchmark Data ◽  
Elastic Bottom ◽  
Structural Deformations ◽  
Two Bodies

Abstract Extensive water entry experiments were performed to identify uncertainties associated with measured impact-induced loads acting on flat bottom ship structures. Of primary concern was the influence of air trapping on elastic structural deformations. The experimental measurements supplied benchmark data suitable to validate CFD predictions. Two bodies were tested. One body was fitted with stiffened, rigid bottom plating; the other body, with thin elastic plating. A large number of 30 repetitive runs recorded bottom pressures and forces acting on the flat bottom plating and monitored impact-induced elastic bottom strains. For each test case, high-speed videos of water entry sequences were evaluated. The resulting average peak values standard deviations quantified the uncertainty of these measurements.

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