Combined Structural Oscillation Effects o:n Solid Rocket Internal Ballistics

The combined effects of radial and axial vibration of the surrounding structure on the internal ballistics of a solid rocket motor are investigated via numerical simulation. A finite-difference model is applied for the radial deformation dynamics of the propellant/casing assembly along the length of the motor, while the nonsteady internal core flow is modelled using a primarily second-order, finite-volume random-choice technique. Predicted nonsteady combustion and flow behavior resulting from an initial pressure pulse within the flow, allied to the free axial and radial oscillation behavior of the surrounding structure, is consistent with experimentally observed trends associated with axial and transverse combustion instability. Instability-related phenomena such as the dc pressure rise and axial pressure wave strength development are demonstrated to be dependent in part on the motor structural characteristics.