Nonlinear characteristics of the triggering combustion instabilities in solid rocket motors

The triggering combustion instability in the solid rocket motor is investigated from a nonlinear dynamical system perspective. A coupling model taking both the nonlinear acoustics in the chamber and the unsteady combustion of the solid propellant into consideration is adopted. Its typical responses to different excitations are compared systematically for varying parameters. The boundaries for the different responses in the parameter space are then investigated from the bifurcation analysis. It is shown that the triggering region of the solid rocket motor, corresponding to the bistable region of the coupling model, is confined by two curves consisting of bifurcation points, which intersects at a high order bifurcation point, the cusp point. The complex geometry of bistable region in multi-dimensional parameter space indicates the influences of parameters on the triggering combustion instability of the solid rocket motor can be quite different. The results suggest a comprehensive consideration on different parameters is needed in evaluating the combustion instability of an solid rocket motor.