Simulation and measurements of muzzle blast overpressure and its physical manifestations are studied in this paper. The use of a silencer can have a great influence on the overpressure intensity. A silencer is regarded as an acoustic transducer and a waveguide. Wave equations for an acoustic dotted source of directed effect are used for physical interpretation of overpressure as an acoustic phenomenon. Decomposition approach has proven to be suitable to describe the formation of the output wave of the wave transducer. Electroacoustic analogies are used for simulations. A measurement chain was used to compare the simulation results with the experimental ones.

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.

Abstract:The aerodynamic data obtained in the static and dynamic wind tunnel tests are presented in this paper. The tests are performed in the T-38 wind tunnel facility of the Military Technical Institute in Belgrade. Normal force and pitching moment in static and dynamic tests are measured using semiconductor five-component strain gauge balance. This specific five-component balance is dynamic derivative balance. Forced oscillation technique is used for the dynamic measurements applied in the T-38 wind tunnel. The wind tunnel data are compared with aerodynamic data determined using flow simulations with RANS (CFD) code and applied models of turbulence. The aerodynamic data calculated using semi-empirical prediction were the initial values for the numerical research. The experimental and numerical data are presented for the one standard missile model (Modified Basic Finner Model) for three flow regime Mach numbers.

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This paper focused on the 12.7 mm gun barrel stress response caused by the pressure of the gunpowder gases. During the firing process, the barrel is loaded by different mechanical, chemical and thermal loads. In this paper except the pressure of the propellant combustion, all the other loads were ignored. The pressure loads are obtained with a mathematical model of the interior ballistic. The Lame equations for the thick-walled cylinder were used to calculate the barrel stress response. The loads are applied on a certain barrel cross-section for a defined time. Two 3D models of the barrel with and without grooves were used to perform a numerical simulation. A comparison between results for the two types of barrels shows a good agreement between the stresses obtained by the analytical and numerical methods.