Análise integrada da balística interna e intermediária em um fuzil de assalto 5,56: ensaio experimental, modelagem numérica e simulação CFD

Abstract

A detailed understanding of internal and intermediate ballistics is a fundamental requirement for the development of long-barreled firearms that balance performance, safety, and acoustic comfort. Within this context, the present work proposes an integrated approach to characterize the firing dynamics of a 5.56 mm Assault Rifle. The research began with an in-depth theoretical review, establishing the mathematical formulation necessary to describe the thermodynamic and kinematic phenomena associated with the transient compressible flow of combustion gases, which govern the projectile’s movement inside the barrel. The numerical modeling of the internal ballistics was implemented in the Matlab/Simulink environment, solving the governing equations using the 4th-order Runge-Kutta method. The validation of this model was anchored in an experimental testing campaign instrumented with HPI GP6 piezoelectric transducers, allowing the acquisition of the chamber pressure curve. The comparison between the numerical results and empirical data attested to the code’s ability to faithfully reproduce the actual ballistic behavior, showing adequate agreement in peak pressure and muzzle velocity values. In a subsequent stage, the validated data from the firing pressure curve provided the basis for a Computational Fluid Dynamics (CFD) analysis using the Ansys Fluent software. This simulation employed dynamic meshes to simulate the projectile’s movement as a function of the pressure acting on its base. Furthermore, native solver models were used to account for real gas behavior. This approach allowed for the visualization and analysis of intermediate ballistics phenomena in a compressible flow regime, an experimental evaluation of which would require a complex and high-cost experimental apparatus. Thus, this work consolidates a robust analysis methodology with direct application in the Research and Development (R&D) of small arms, providing essential data for the design of complex components such as sound suppressors and muzzle brakes.