Effect of Fluid/Structure Coupling on Unstable Mechanisms in a Solid Rocket Motor

The influence of fluid/structure coupling in a subscale model has been investigated in the framework of solid rocket motor instability. The first self-sustained oscillations of the flexible membrane were identified, and it was found that the flapping motion strengthens the laminarization process in the obstacle's wake vortex shedding. In addition, the equilibrium between vortices in the shear layer and wall vortex shedding is modified and instability is favored by introducing a flexible membrane. Introduction of the forced oscillating motion of the inhibitor gives rise to similar conclusions. However, a significant lessening of the unstable process was noted when the flexible membrane exhibited specific characteristics.