Vortex shedding in segmented solid rocket motors

This article is devoted to the numerical simulation of vortex shedding in the field of solid-propellant rocket motors resulting from the strong coupling between the shear-layer instability and acoustic waves in the chamber. Segmented solid rocket motors tend to develop thrust and pressure oscillations, linked to a periodic vortex shedding. An axisymmetric geometry close to the realistic configuration is computed. The computer code solves the unsteady Navier-Stokes equations by means of an explicit predictor/corrector MacCormack scheme. Mesh dependence is studied by using three grid levels, In all cases, the vortex shedding process is observed. This mechanism is complex and vortex pairing, occurs. The viscosity effect is analyzed by using three different viscosity values. The effect of the shape of diaphragms on vortex shedding is also studied by comparing sharp and smooth diaphragms.