Comprehensive view of the combustion models of composite solid propellants

Introduction C solid propellants contain an inorganic oxidizer (generally ammonium perchlorate, AP) and a fuel binder (organic polymers) as the major ingredients. In order to understand the combustion phenomena of the propellant in its totality, it is worthwhile to examine the combustion of the ingredients, i.e., AP and the polymer, as a prelude to the propellant combustion. Some attempts have been made in the past to understand the combustion of AP, which also happens to be a monopropellant, and some similarities have been shown to exist between the combustion of AP and the combustion of the propellant. The binder combustion, from the viewpoint of propellant combustion, has not received adequate attention, which may perhaps be due to the belief that the binder occupies a smaller proportion in the propellant. However, combustion and physicochemical characteristics of a propellant do depend on the nature of the binder. Thus, there is a need to understand the combustion of AP and the polymer separately. Since the information available in the literature on the various aspects of combustion of the binder, AP, and the propellants is fragmentary, it is the purpose of the present review to bring together the information and examine it critically.