Flame-Spreading Process in Solid Rocket Motor with Fin Slots

This paper presents a numerical framework for simulating the transient flame-spreading process during the ignition of solid rocket motors with geometrically complex configurations. The approach incorporates various physical models, including a three-dimensional flow model, convective and radiative heat transfer models, a solid-phase thermal diffusion model, a pyrolysis model, and a flame sheet model. The accuracy of this method is validated through a ground-firing test of a solid rocket motor (SRM) with fin slots. This study focuses on the impact of the igniter port configuration, particularly its canting angle and rotational angle relative to the fin slot, on the ignition performance of SRMs. Results indicate that as the canting angle increases, three distinct flame-spreading modes are observed, with minimal variation in behavior exhibited within each mode as the angle changes. At a moderate canting angle, flame spreading within the head-end fin slot is the fastest, while it is the slowest in the aft-end fin slot. Because flame spreading within the aft-end fin slot significantly affects pressure variations, this condition results in the lowest pressure rise rate. Adjusting the rotational angle of the igniter port relative to the fin slot exerts no significant influence on the ignition process.