Numerical Study of the Effects of Longitudinal Acceleration on Solid Rocket Motor Internal Ballistics

The internal ballistics of a solid-propellant rocket motor subjected to both constant and oscillatory longitudinal accelerations are studied. The one-dimensional time-dependent equations of motion governing the unsteady two-phase core flow in the accelerating motor chamber and nozzle are solved numerically by using the random-choice method, along with pressure-dependent and crossflow-dependent burning-rate equations for propellant combustion. A constant forward acceleration produces negligible effects, whereas longitudinal motor vibrations near the natural frequency of waves criss-crossing the length of the motor chamber can produce large but bounded oscillatory motor-chamber pressures.