Analysis of the Effect of Circular Ring Baffles in Suppressor on Flow Field and Far Field Noise Levels at 9 mm Semi Automatic Pistol

A firearm generates complex phenomena in muzzle flow and modelling the flow field around the projectile has great importance on high-intensity noise prediction. The negative effects of noise can be reduced using a suppressor which can be internally or externally attached to the barrel of a firearm. The purpose of this paper is to numerically and experimentally investigate the effect of the number and distance of circular ring baffles in the suppressor on the flow field and far field noise levels. Calculations were carried out in two-dimensional, axisymmetric, transient conditions and Ffowcs Williams and Hawkings acoustic analogy (FW-H) equations were solved to predict the far field noise. Nine cases including a gun without a suppressor, a suppressor without baffles, one, three, and five baffles which were placed at 20 mm intervals from the suppressor inlet, and one, three, five, seven, and nine baffles which were placed with equal intervals in the suppressor were simulated and compared; generations of noise during the shooting process were analyzed. The results showed that in the case without a suppressor, the peak sound pressure level was 156.1 dB at a 2.5 m distance, while this value decreased by nearly 7.6% in the case of the suppressor with seven baffles which has an average value of 144.2 dB. The results obtained here may provide a beneficial reference for predicting the muzzle noise and optimizing the number of baffles in the suppressor for small caliber gun systems

Application of a CFD Model in Determination of the Muzzle Blast Overpressure in Small Arms and Its Validation by Measurement

The main subject of this paper is application of a Computational Fluid Dynamics (CFD) model in determination of the muzzle blast overpressure and its physical manifestations, as well as its validation through measurements of primary parameters. Unsteady Reynolds-averaged Navier-Stokes equations (URANS) with a corresponding turbulence model were applied for numerical simulation of complex gas-dynamic process of propellant gases release from the barrel after firing. The unstructured adaptive mesh for spatial discretization was applied, as suitable model for numerical calculation and physical interpretation of these intensive dynamic processes. The provided experimental results were compared with the results of numerical simulations, which were thus validated, according to adopted minor simplifications

Axial-Symmetry Numerical Approaches for Noise Predicting and Attenuating of Rifle Shooting with Suppressors

The moving bullet out of a rifle barrel is propelled by a fired explosive charge. Subsequently, a disturbed muzzle blast wave is initiated which lasts several milliseconds. In this study, axially symmetric, unsteady, Large Eddy Simulation (LES), and Ffowcs Williams and Hawkins (FWH) equations were solved by the implicit-time formulation. For the spatial discretization, second order upwind scheme was employed. In addition, dynamic mesh model was used to where the ballistic domain changed with time due to the motion of bullet. Results obtained for muzzle flow field and for noise recorded were compared with those obtained from experimental data; these two batches of results were in agreement. Five cases of gunshot including one model of an unsuppressed rifle and four models of suppressors were simulated. Besides, serial images of species distributions and velocity vectors-pressure contours in suppressors and near muzzle field were displayed. The sound pressure levels (dB) in far field that were post-processed by the fast Fourier transform (FFT) were compared. The proposed physical model and the numerical simulations used in the present work are expected to be extended to solve other shooting weapon problems with three-dimensional and complex geometries