At certain conditions, propelling charges for artillery – either because of their low heat of combustion, a low vulnerability, or due to other reasons – require relatively high initiation thresholds. This phenomenon, combined with large gun chambers, high initial charge densities of materials with granular geometry and low porosity powder beds, give rise to delays and irregularities in the initiation times at various points of the propelling charges. These irregular behaviors or failures in the initiation cause pressure waves within the chambers of the weapons. This paper focuses on experimental studies and tests carried out on the processes taking place in the initiation of propelling charges, which can lead to pressure waves in the bore of howitzers and cannons. Pressure waves during initiation are considered to be particularly dangerous to the safety of users and weapons. The behavior of the initiator systems, the flame volume and its distribution throughout the length of the bore are analysed by means of pressure‐time diagrams, obtained from experimental shooting. The data are processed using the standard Fourier transform and the “discrete wavelet transform”, by means of the Daubechies functions. This allows to identify when these events occur during shooting and to determine some of the causes in order to achieve virtual elimination of the pressure waves.
A model to analyse the heterogeneous combustion process that takes place in an axisymmetric combustor of an air ducted rocket is presented, including radiation. The fuel, injected into the combustor through a simple injector, is a mixture of gaseous products, carbon particles, and MgO inert particles that results from the combustion of a solid fuel (HTPB-AP-Mg). The turbulence model used is the realizable k—π model. The adopted reaction model is a reduced kinetic scheme composed of five reactions, three in gaseous phase and two heterogeneous. The model ‘finite rate/eddy dissipation model of Magnussen and Hjertager’ is used to calculate the production terms in the gas phase, meanwhile the mixed model of Field, Baum, and Street is used for the oxidation reaction of carbon particles. After a detailed analysis of the numerical results, obtained with a commercial code for a specific combustor geometry and one set of boundary conditions both for the gaseous and solid phases, the existence of a special combustion pattern is found. It is composed of a turbulent diffusion jet flame attached to the injector, where only the gaseous fuel is burned, followed by a reaction region that envelops the jet of carbon particles at the aft of the combustion chamber. This jet of carbon particles oxidizes at a finite rate producing CO and CO2. The emission of CO and C(s) from the combustor is the main cause of high efficiency reduction. Radiation has little effect on calculated global variables, such as efficiency, mass flowrate, and total pressure loss, but on the contrary its effects on the temperature fields became important. Chilling of the gas phase was observed together with a reduction of solid particle temperature, however wall combustor temperature increased greatly. Simulation results are interpreted in the light of experimental observations and available numerical solutions in the literature.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.