A detailed analysis of the characteristics and stability of the trajectory of a high-speed projectile during water entry is investigated numerically. The Zwart–Gerber–Belamri cavitation model and the shear stress transport k–ω turbulence model based on the Reynolds-averaged Navier–Stokes method are employed. The numerical method is validated by comparison of its results with the experimental images of cavity shape and with measurements of the penetration distance. Using this numerical method, the influences of rotational speed, initial velocity, and water-entry angle of the projectile on the stability and characteristics of its trajectory are investigated. The variations in projectile trajectory, total drag, and velocity reduction are analyzed. In addition, the cavity characteristics at water entry are presented and analyzed. The results show that the rotation of the projectile has an adverse influence on the stability at water entry, although the magnitude of the rotational speed has little effect on the reduction in projectile velocity. The initial velocity of the projectile has a direct effect on the trajectory stability. It is also found that in practice, there should be a critical water-entry angle for the stability of a projectile.

中文翻译：

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高速进水弹丸弹道特性的数值研究

数值研究了高速弹丸入水过程中弹道的特性和稳定性。所述兹瓦特-格柏-Belamri空化模型和剪切应力运输ķ - ω采用基于雷诺平均Navier-Stokes方法的湍流模型。通过将其结果与腔体形状的实验图像以及穿透距离的测量结果进行比较，验证了该数值方法的有效性。利用这种数值方法，研究了弹丸的转速，初始速度和进水角对弹丸稳定性和弹道特性的影响。分析了弹道，总阻力和速度降低的变化。此外，介绍和分析了入水腔的特性。结果表明，弹丸的旋转对入水稳定性有不利影响，尽管旋转速度的大小对弹丸速度的降低影响很小。弹丸的初始速度直接影响弹道的稳定性。还发现，在实践中，对于弹丸的稳定性，应该有一个临界的水进入角。