Numerical study on two dimensional adiabatic microscale combustion model for solid propellant

In order to realize integrated simulation on solid propellant microthruster's working process, based on the computational software Fluent and reduced chemical kinetic mechanism, a 2D adiabatic microscale combustion model taking into consideration both gas reactions and condensed phase reactions was built, which contained two condensed phase reactions and five gas phase reactions of a double base solid propellant tested in a solid propellant microthruster. The burning rate, temperature of burning surface and species mass fraction were derived by calculating physics properties at and near propellant's burning surface. The viscosity effect on gas phase reactions and condensed phase reactions was also taken into consideration. Calculation was performed for four different atmosphere pressure values: 0.5MPa, 1.0MPa, 2.0MPa and 5.1MPa, respectively. Results show that the flame zone emerges in high pressure atmosphere, moving nearer to burning surface of the solid propellant when pressure gets higher, and the thickness of condensed phase reaction zone diminishes with the rising of atmospheric pressure, together with mass fraction of major reactants of reactions in fizz zone and dark zone at the burning surface. The burning rate, burning surface temperature of the propellant and gas phase flame structure basically align with experimental results at the symmetry. Due to viscous effect at the wall, the flame moves nearer to burning surface at the wall than at the symmetry, which led to higher burning rate of solid propellant at the wall than at the symmetry. The model realized integrated simulation of a solid propellant's 2D adiabatic combustion model taking the multi-step condensed phase reactions into consideration and it well extended the application field of the original combustion model.