Numerical Modelling of Caseless Ammunition with Coreless Bullet in Internal Ballistics

Abstract

In the search of a new weapon for combat in short range, it is proposed the use of a new experimentally designed 7.62 mm calibre ammunition with a lighter weight (caseless-coreless). This can be used in carbine assault rifles with short barrel or pistols. In this work, the compressible gases flowing through the gun barrel caused by the proposed ammunition were experimentally and numerically analysed. The Large Eddy Simulation was used for the numerical simulation, considering a compressible and turbulent flow, with the chemical species transport model and a complete conversion of the propellant reaction. Variations in pressure and temperature were compared with the results obtained from a conventional 7.62 mm full metal jacket (FMJ) ammunition. Results of ballistic experimental tests and numerical simulations were similar than those of the 9 mm x 19 mm FMJ ammunitions, showing feasibility for the development of new weapons intended for operations of short range shots.

Internal ballistics of polygonal and grooved barrels: A comparative study

“…In this case, the experimental curve does not show a first pressure peak from the primer ignition, unlike the pressure tests carried out by Silva-Rivera et al 14,15 to 7.62 mm × 51 mm cartridges. This is because 9 mm × 19 mm ammunition has a lower volume inside, with a powder charge of 0.30 g, so it is ignited entirely by the primer, reaching maximum pressure simultaneously.…”

“…In this study, it was not possible to obtain an experimental pressure curve for a hexagonal barrel, since there is no agreement to standardize a polygonal test barrel. The pressure curves obtained by numerical analysis are also presented for firing in In this case, the experimental curve does not show a first pressure peak from the primer ignition, unlike the pressure tests carried out by Silva-Rivera et al 14,15 to 7.62 mm 3 51 mm cartridges. This is because 9 mm 3 19 mm ammunition has a lower volume inside, with a powder charge of 0.30 g, so it is ignited entirely by the primer, reaching maximum pressure simultaneously.…”

“…The pressure is obtained in the chamber, in the same location where it is experimentally measured in standardized barrels, which have a slot 21 mm from the rear of the barrel, in which a piezoelectric transducer is located to measure the pressure. [22][23][24] In this case, a turbulent flow regime and the Eddy-dissipation model is considered, being expressed by: 15,25…”

“…The eight subsequent analyzes were carried out with 20 mm increments in the bullet position and the last one of 15 mm, to reach the final length of the barrel 200 mm. This procedure is described in detail by Silva-Rivera et al 15 Besides, the conditions of the system were specified, such as the specific heat ratio at 1.2105, the density of the double base powder of 210 kg/m 3 , the stagnation temperature of 2200°K, and the maximum chamber pressure of 230 MPa, according to the STANAG-4090 standard. 22 The second type of numerical analysis was performed with the Finite Element Method to obtain Velocity, Deformation depth, Deformation width, Equivalent Plastic Strain, and Equivalent Stress.…”

Numerical and Experimental Analysis of Sound Suppressor for a 5.56 mm Calibre

“…The design proposals were constructed from the study of technical principles in acoustics 12,13 , the study of Werbel & Berth patents 14,15 , and the analysis of principles and evaluation methods for silencers as presented in 16 . The principles of design, manufacture, and modelling of mechanical systems [17][18][19] were analysed to comply with the permissible noise limits (MIL-STD-1474E) 20 . During the establishment of the work methodology, the main component from which the design should start is the human being [21][22][23] .…”