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Proof of Pyrotechnic Ammunitions
Published in Ajoy K. Bose, Military Pyrotechnics, 2021
Each proof range is equipped with various firing euipments and performance measuring instruments. Static proof requires a short range. while dynamic proof requires long range and wide area as it proves the ammunition in dynamic mode and the range varies as per the ammunition. For example, with available ammunition in the ammunition industry, 51-mm ammunition would require minimum range of +2 km; an 81-mm would require a minimum range of +6 km while a 155 mm would require a minimum range of +32 km. However, the actual requirement of range is much more than the above values to allow for any wild round for safety reasons.
Modeling Dissolution of High Explosive Formulations
Published in Soil and Sediment Contamination: An International Journal, 2018
The TNT particles were collected from a low-order (LO) detonation of a 155 mm artillery round. Each HE particle rested on a 10-mm-diameter glass frit at the base of a Buchner funnel that drained into a 20- or 40-mL scintillation vial. Water was dripped onto two TNT particles (in separate frit-funnel apparatus) with flow rates that averaged 0.47 mL/hr (26 drops/hr) for particle 1 and 0.95 mL/hr (56 drops/hr) for particle 2, which were equivalent to nominal rainfall rates of 5.9 and 12.0 mm/hr (51.7 and 105.1 m/yr), respectively, based on the surface area of the frit. Assuming spherical shape, the water drop diameters for particle 1 and 2 were computed to be 3.28 and 3.21 mm, respectively. The initial TNT mass of particle 1 and 2 was 5.34 and 9.59 mg, respectively. Essentially all of the TNT mass was dissolved in 201 days for particle 1 and 98 days for particle 2. The model was applied with a TNT density of 1.65 g/cm3 and TNT solubility of 119 mg/L based on the test temperature of 22°C and the Phelan et al. (2002) solubility regression. Assuming spherical shape, the diameters of particle 1 and 2 were computed to be 1.84 and 2.23 mm, respectively. Thus, with the water drops being larger than the particle sizes, the Lever-Taylor small-particle, drop-impingement model would be appropriate. However, the present model, which is a variation of the large-particle, drop-impingement model, was developed for natural field conditions where a large particle drop-impingement model can be more applicable than a small particle model since rain drops are on the order of several millimeters, and HE particle residue is on the order of a centimeter (Pennington et al. 2005 and Taylor et al. 2004). With the frit diameter being three times larger than the water drop diameters, it was necessary to determine an effective rainfall rate in order to use the experimental results with the present model, rather than using the nominal rate based on frit surface area.
Interval uncertain optimization for interior ballistics based on Chebyshev surrogate model and affine arithmetic
Published in Engineering Optimization, 2021
Fengjie Xu, Guolai Yang, Liqun Wang, Quanzhao Sun
Using the established one-dimensional two-phase flow interior ballistic model, the interior ballistic problem of a 155 mm howitzer was solved. The propellant mass is 15.5 kg and the projectile mass is 45 kg. The obtained projectile velocity curve and its comparison with the results in Ma and Zhang (2013b) are shown in Figure 2.
A Hotspot Model for PBX Explosive Charge Ignition in a Launch Environment.
Published in Combustion Science and Technology, 2020
Wei Liu, Guoping Wang, Xiaoting Rui, Jian Gu, Xin Zhao
In this paper, the internal stress of explosive charge is obtained by accurately calculating the movement process of the projectile and analyzing the mechanical environment in the bore. On the basis of the 1D hollow sphere pore-collapse model established by Withworth, considering explosive chemical reaction, heat conduction, phase transition, and viscoplastic deformation processes during the launching process, the 1D hollow sphere pore-collapse model in a launch environment is established, which reveals the ignition mechanism of explosives and describes the hot spot formation in launch environment. Finally, taking as the ignition threshold of explosives, a practical and effective method for determining the ignition of explosives is proposed, contributing to the launch safety determination and performance evaluation of explosive change. The simulation results of the interior ballistic process of 155 mm howitzer based on the finite element method show that the axial stress reaches a maximum at the bottom of an explosive charge, where it is easy to generate hot spots.Based on the 1D hollow sphere pore-collapse model, the hot spot formation process of an explosive charge in the launch environment of 155 mm howitzer is simulated. Then, the results illustrate that the temperature of explosive increase depends on the viscoplastic work, chemical reaction, gas compression, and heat conduction.According to the positive correlations between the temperature peak at the surface of collapsing pore and , the can be used as the ignition threshold of explosive. As to the 155 mm howitzer launching process, explosives are not ignited until =0.8.Based on the threshold of , a method to determine the launch safety of explosive charge is established, which provides an effective and practical ideal for the charge designer.