Resumo:
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.
