Numerical solution of solid propellant unsteady burning

A numerical method to solve the equations governing unsteady propagation of monodimensional heterogeneous deflagration waves is discussed. Essentially, the problem consists of a nonlinear parabolic partial differential equation, with time varying boundary conditions, describing thermal diffusion in a semi-infinite medium with variable properties. Condensed phase and burning surface can be modelled according to arbitrary but assigned laws; gas phase is described by any thermal model of quasi-steady flame. Forcing functions can be any combination of pressure and radiant flux (emitted by an external source), however varying in time but assigned. The numerical code set up was successfully applied, under various operating conditions, to simulate a wide spectrum of physical phenomena (ignition, extinction, self sustained oscillations, relaxation toward steady states) associated with solid rocket propellant butning,