Computational Analysis of an AK-47 Bullet Proximate to Stationary, Moving, and Porous Wall

Abstract

In firearms and ballistics, grasping the interaction between high-speed projectiles and their surroundings is crucial for optimizing trajectory, stability, and accuracy. This study explores the comparison of intricate flow dynamics involved when a bullet, traveling at the Mach number equal to 2, is fired near both a moving object or wall and a stationary wall, particularly in urban warfare scenarios. The proximity to the wall introduces an asymmetry in the pressure distribution across the bullet’s body, affecting its flow physics in diverse ways. The present analysis employs Computational Fluid Dynamics to scrutinize the flow field around a 7.82-mm bullet from an AK-47 rifle moving at supersonic speeds near the ground. Computational simulations explore phenomena at various heights from a nearby stationary or moving wall, ranging from the region of nearest influence to a ground distance five times the bullet’s diameter. The study encompasses height-to-diameter ratios h/D from 0.5 to 5, shedding light on the overall flow field, the pressure coefficient distributions, and the lift, drag, and moment coefficients. Additionally, the flow field in the wake region is examined. The results highlight the generation of a detached bow shock wave at the bullet’s tip, significantly influencing the drag coefficient experienced by the projectile. This study contrasts the effects of a stationary wall at varying proximities to the ground with those of a moving wall at equivalent distances. The comparison highlights change in flow characteristics and various parameters, providing valuable insights into high-speed projectiles in proximity to stationary walls and moving walls simultaneously (h/D) at a Mach number 2 during urban warfare scenarios. Furthermore, a study on the effect of porous wall proximity to the bullet has been conducted, and the shock absorption reduces the momentum. Understanding these phenomena is crucial for optimizing the bullet design and enhancing the effectiveness of missile ballistics in real-world applications.