Modeling the combustion of JA2 and solid propellants of similar composition

A theoretical study on combustion of JA2, RPD-380, and RPD-351, which are modified double-base propellants composed primarily of three identical nitrate ester ingredients, is presented. A one-dimensional, two-phase model was used [M.S. Miller, W.R. Anderson, in: V. Yang, T.B. Brill, W.Z. Ren (Eds.), Solid Propellant Combustion Chemistry, Combustion and Motor Interior Ballistics, Progress in Astronautics and Aeronautics, vol. 185, AIAA, Reston, VA, 2000, pp. 501–531, (a) M.S. Miller, W.R. Anderson, J. Propul. Power 20 (3) (2004) 440–454. (b) M.S. Miller, W.R. Anderson, CYCLOPS, A Breakthrough Code to Predict Solid-Propellant Burning Rates, U.S. Army Research Laboratory Technical Report, 1987 ARL-TR-2910.]. This approach has been shown to give good agreement between predicted and experimental results for several nitrate ester propellants, including JA2 [(a) M.S. Miller, W.R. Anderson, J. Propul. Power 20 (3) (2004) 440–454. (b) M.S. Miller, W.R. Anderson, CYCLOPS, A Breakthrough Code to Predict Solid-Propellant Burning Rates, U.S. Army Research Laboratory Technical Report, 1987 ARL-TR-2910.]. Extension of the model to the two RPD variants yields results in good agreement with existing experimental data. Comparisons of the response of predicted burning rates to experimental formulation changes at gun pressures, and to the initial propellant temperature are particularly encouraging. Our results show the burning rate ordering of these propellants is JA2 < RPD-380 < RPD-351 at all pressures. Chemistry which appears to account for this ordering is discussed. Also, an upgraded mechanism was used, and the reasons for some slight changes in results vs. an older one are identified. Sensitivities of the computed temperatures near the propellant surface to the various reactions’ rate coefficients are discussed; these provide insights regarding which reactions are centrally important to the computed burning rates and solutions. The spatial structure of one propellant flame – temperature and species profiles – is given; variations vs. the formulations and pressure are discussed. The fidelity of burning rate response to mixture ratio and initial propellant temperature are encouraging that the model may find application in propellant formulation science and elsewhere.