Nonsteady interior ballistics of cylindrical-grain solid rocket motors

A numerical model for the prediction of undesirable axial combustion instability symptoms in solid-propellant rocket motors is presented. The unsteady interior flow in the motor chamber, the oscillation of the surrounding structure of the propellant and motor casing, and the corresponding transient combustion process, are all incorporated within this model. The dynamic combustion process is modelled via the Zeldovich-Novozhilov solid-phase energy conservation approach, with a burning rate limiting function that allows for an applicable alignment with observed experimental combustion response characteristics of a given propellant. Example results from the overall numerical model are presented for cylindrical-grain motors having differing characteristics with respect to geometry and burning rate.