Effects of AP powder topology on microscale combustion properties of AP/HTPB propellant

A three-dimensional model has been developed to capture burning properties of ammonium perchlorate(AP)/hydroxyl–terminated polybutadiene(HTPB) composite propellant. Interfacial coupling between condensed domain and gas phase was conducted to obtain the surface temperature and burning rate. The condensed phase was governed by heat transfer equation, and reacting Navier-Stokes equations with pressure dependent 3-step and 12-species global kinetics were adopted. The current model was verified and validated by comparing with analytical and experimental results. Thereafter, the influences of ellipsoidal AP's orientation and aspect ratio on the burning rate were investigated. The flame structure of a typical propellant with ellipsoidal AP particle was examined, and the characteristic heights of multiple flames were determined. Besides, the flame properties of a typical propellant with spherical/ellipsoidal AP particle and different AP topologies were analyzed. Furthermore, the temperature sensitivity coefficients were calculated for composite propellant with different AP contents and sizes, matching reasonably with the experimental results.