This study addresses some aspects regarding water jet propulsion during high explosives detonation. A number of theoretical and experimental studies have shown that using Gurney equation and the relationships derived, one can provide fair results regarding initial velocity of metallic fragments for explosively‐driven metal casings. However, an investigation on Gurney equations utilization for the prediction of water velocity has not been performed yet. By carrying out simple experimental tests and numerical simulations, water has been investigated in terms of total mass average velocity and tip velocity. Based on the available data, the findings indicate that Gurney equations overestimate the water mass average velocity. For water tip velocity evaluation, further studies should be made.
A series of methods were employed to assess the performances of advanced coating materials based on components that can modify the spectral parameters of the surfaces on which these materials are applied in order to obtain passive military camouflage. Powder materials with high infrared (IR) reflectance were used to obtain this type of coatings, which also ingrain in their structure a significant volume of air that allow limitation of the radiative heat transfer of the coated source. The components were embedded in a polyurethane matrix, which facilitated the coating process on different surfaces. The bicomponent polyurethane-based binder used within the different composition tested is transparent to incident IR radiation, has no organic solvents, is highly flexible and possesses remarkable physical, chemical and mechanical properties: high surface adhesion, high flexibility and resistance against a number of chemical agents and external factors with destructive effect. The efficiency of these composite materials was further demonstrated by analyzing the thermal images of different objects.
The present paper presents both experimental and simulation conducted results in case of a thermobaric projectile for SPG-9 recoilless rifle, caliber 73 mm. The simulation consists in determining main forces such as aerodynamic drag, lift, and other parameters like the center of pressure, the center of mass and inertial moments, etc. On the other hand, the experimental results consisted of performing a series of firing, with real and inert rocket engines, during which the velocity of the projectile was measured. The values obtained were subsequently used to validate the numerical simulation.
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