Catalytic effects of nano additives on decomposition and combustion of RDX-, HMX-, and AP-based energetic compositions

This volume brings together international scientists in the field of solid rocket propulsion. Thirty-nine papers present in-depth coverage on a wide range of topics including: advanced materials and non-traditional formulations; the chemical aspects of organic and inorganic components in relation to decomposition mechanisms, kinetics, combustion and modelling; safety issues, hazards and explosive characteristics; and experimental and computational interior ballistics research, including chemical information and the physics of the complex flow field.

Solid propellant chemistry, combustion, and motor interior ballistics

https://www.yang.gatech.edu/publications/Journal/PECS%20(Beckstead,%202007).pdf

Modeling of combustion and ignition of solid-propellant ingredients

Benfield, et al. (1972) showed that among fixed-interface, free-interface, and hybrid substructure coupling methods, the fixed-interface methods as the most accurate and the free-interface methods are the least accurate. In the present note, a substructure coupling method is proposed which employs free-interface substructure modes supplemented by 'reduced flexibility.' Substructure coupling based on the improved substructure model is discussed, and a numerical comparison with Hou's free-interface method is given. To simplify representation of the method proposed, the substructure equations are developed first for constrained substructures, and then the equations representing substructures with rigid-body modes are given. Finally, the equations for coupling of substructures are derived. Example calculations are included.

Free-interface methods of substructure coupling for dynamic analysis

Study of aluminum particle combustion in solid propellant plumes using digital in-line holography and imaging pyrometry

A model describing the combustion of AP composite propellants has been developed. The model is based on a flame structure surrounding individual oxidizer crystals; the relationship between crystals and the binder matrix being evaluated statistically. Three separate flame zones are considered: 1) a primary flame between the decomposition products of the binder and the oxidizer, 2) a premixed oxidizer flame, and 3) a final diffusion flame between the products of the other two flames. Simple global kinetics are assumed for gas-phase reactions, and the surface decomposition of the propellant ingredients is assumed to be adequately described by simple Arrhenius expressions. The oxidizer decomposition is taken as being the over-all controlling factor in the combustion process. The results obtained show that the calculated surface temperature and the effect of oxidizer concentration predicted by the model are in agreement with observed experimental trends. The predicted effect of particle size is somewhat greater than observed experimentally while the temperature sensitivity is in excellent agreement with experimental data. The results of the calculations indicate a relatively strong exothermic reaction taking place at the propellant surface. Apparently the ammonium perchlorate (AP) partially decomposes exothermically in the thin surface melt previously reported in AP deflagration studies.

A model of composite solid-propellant combustion based on multiple flames

A model describing the combustion of composite propellants has been applied to three different types of composite propellants, and to two oxidizers which burn as monopropellants. The oxidizers studied are AP, HMX, and KP (ammonium perchlorate, cyclotetramethylenetetranitramine, and potassium perchlorate), each of which has unique combustion characteristics. The monopropellant combustion of AP and HMX has been considered in detail, particularly that of AP. Calculations have been compared with experimental data for the burning rate, the sensitivity of the burning rate to both pressure and initial temperature, and the surface temperature. The agreement between the calculations and experimental data is very adequate. The results indicate that AP and HMX apparently burn with a considerable exothermic reaction at the burning surface as well as in the gas phase above the surface. Both reactions must be accounted for to give consistent results. The combustion of the three oxidizers burning with a fuel in composite propellants has also been simulated. Experimental data are presented for propellants in which the oxidizer has been systematically varied. A direct comparison has been made between the data and the calculations of the model. The calculations agree quite well with the combustion characteristics of the three different types of composite propellants.

R. L. Derr

Papers

A model of composite solid-propellant combustion based on multiple flames

The combustion of solid monopropellants and composite propellants