Abstract
ABSTRACTThe significant influence of the ground on the hypervelocity jet flow as well as the stability of the projectile cannot be discarded due to the intensity and the wide influence range. The present study examines two three-dimensional simulation models, one with the ground effects included and the other without, based on FLUENT software, using the finite volume method (FVM). The simulation models couple the FVM model with a standard k-ε turbulence model and unstructured dynamic grid based on the Local Remeshing method. An intermediate ballistic model and the six-degrees-of-freedom model are also utilized. For the 300-caliber 1730 m/s countermass propelling gun, two different flow phenomena, with and without the ground effects, were examined. The simulation results indicate that the effect of the ground surface on the jet flow and the projectile emerged gradually at 1.5 ms. The hypervelocity muzzle shock wave was reflected off the ground, creating a new shock-wave phenomenon in the opposite direction. The wave system interacted with the muzzle shock wave so that the pressure in the lower half of the domain was significantly higher than that in the upper half. This phenomenon produced a complete shock-wave surface. Shock waves at the ground produced a vortex, which gradually expanded and developed. The wavefront, which was formed by the ground reflection, led to a new wavefront, producing vortices at the wavefront and propagated towards the front and rear of the main shock wave. The hypervelocity jet flow twisted and generated a more complex wave system. The distorted gas jet caused the projectile to be disturbed, and the lift and torque were influenced so that the parameters such as the angular velocity of the rotation were changed.
Highlights
Research regarding flow shock waves induced by firepowered projectiles is well established due to the practical applications
The present study examines two three-dimensional simulation models, one with the ground effects included and the other without, based on FLUENT software, using the finite volume method (FVM)
The simulation models couple the FVM model with a standard k- turbulence model and unstructured dynamic grid based on the Local Remeshing method
Summary
Research regarding flow shock waves induced by firepowered projectiles is well established due to the practical applications. Recent advances in computational fluid dynamics techniques have made numerical simulations of these complex flow fields a highly effective alternative to experimental studies. A numerical simulation of 122 mm vehicular artillery flow field undertaken by Jiang and Wang (2010) obtained qualitatively accurate results, and the flow phenomenon of 713 m/s. Previous studies on the muzzle flow fields did not take the ground into consideration, and all of them were full-space symmetric numerical simulation models. This study examines two 3D simulation models, with and without the ground, to analyze the ground effects on a hypervelocity jet flow of a 300-mmcaliber 1730 m/s countermass propelling gun, with a particula focus on flight stability. The research will result in a theoretical foundation for experiments on large-caliber hypervelocity countermass propelling guns
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