Numerical analysis of flow instability in segmented SRM

In order to investigate the flow instability in a segmented SRM(solid rocket motor), numerical analyses based on LES(large eddy simulation) were carried out for a potential pressure oscillation characteristics in the chamber when the burning surface regression was at 0 mm, 160 mm and 280 mm, respectively. The numerical results indicate that initial stage flow instability is mostly caused by the parietal vortex-shedding in the chamber shortly after the motor firing. As the burning surface regresses continuously, the restrictors expose to the hot gases. The chamber flow instability is mostly induced by the obstacle vortex-shedding generated due to the effects of the residual annular thermal protection. Correspondingly, the frequency of pressure oscillation is decreased gradually as compared with that of initial stage.