Effect of particle orientation on the burning rate of ammonium-perchlorate-based solid propellants

This paper addresses the effect of oxidizer particle orientation on the burning rate of ammonium-perchlorate-based heterogeneous solid propellants. Mesoscale numerical simulations are conducted assuming that oxidizer particles are ellipsoidal and have different orientations with respect to the combustion direction. The particle orientation is found to produce a significant effect on the burning rate, up to 5–10% depending on the particle aspect ratio or particle loading. Particles aligned normal to the combustion surface are found to burn faster than those aligned parallel to this surface. This strong impact of the orientation can help explain the well-known hump effect in solid propulsion.