THEORETICAL AND EXPERIMENTAL-STUDY OF COMPOSITE SOLID-PROPELLANT COMBUSTION

A burning rate law is proposed to relate the overall burning rate of c omposite solid propellant to the burning rates of individual component s and the geometry of the burning surface. The complex three dimension al burning surface structure is simplified into unit cells in order to allow computational investigation of the mixing mechanism near the bu rning surface. The conservation equations of mass, momentum and mixtur e fraction have been solved numerically to obtain the velocity and-mix ture fraction field above the surface. The averaged mixture fraction o n the burning surface of oxidiser and of the binder is correlated with both the surface geometry and Reynolds number. Experimental results f or detailed surface structure and burning rate for specially formulate d ammonium perchlorate (AP) composite propellant grains have been obta ined at different pressure. The experimental results are explained usi ng the averaged mixture fraction on the surface. It is concluded that the combustion of AP composite propellant is strongly influenced by th e diffusion process near the surface; the large AP particles burn esse ntially as that of monopropellant AP at high pressure; the burning rat e of the mid-size AP particles is augmented by the diffusion process a t all the pressures investigated; and the overall burning rate is cont rolled by the burning rate of binder and that of mid-size AP particles .