Biglobal stability analysis for the side-induced flow in solid rocket motors

A general linear stability approach was applied to investigate the aerodynamic stability of the side-induced flow in solid rocket motors with large length to radius ratio. The eigenvalue problems were discretized by a spectral collocation method and then solved numerically using MatLab software. The discrete eigenvalue set and corresponding eigenfunctions were obtained. Results reveal that when length to radius ratio (L/R) is larger than 10, some eigenmodes become temporal instable. The amplitudes of disturbance velocities increase with the axial locations and instable areas spreading toward the center line, which are consistent with experimental observations. Comparisons between theoretical results and experimental data also show well agreement in the frequencies of disturbance velocities.