EXPERIMENTAL ANALYSIS METHOD OF THE TRANSIENT BURNING RATE OF SOLID PROPELLANT UNDER RAPID PRESSURE CHANGES

摘要

The term transient burning is used to describe the burning behavior of solid propellants that occurs under rapid pressure changes. In solid rocket propulsion systems, the instantaneous burning rate of a solid propellant under rapidly changing non-steady pressure could be significantly different from the steady-state burning rate corresponding to the same instantaneous pressure. This paper reports on a new method of measurement of transient burning rates together with a brief description of the experimental setup. A rapid rise in the chamber pressure was attained by using a pyro pulser added onto a specially designed forward closure of a laboratory-scale test motor that was originally used to measure the steady-state burning rate. The steady-state burning rate as well as the burning rate measured under transient pressure conditions are obtained indirectly by computing from the pressure/time history and applying the small-motor measurement method. In this way, the transient burning rate has been measured in the same motor and by applying a similar method as used for the steady-state burning rate. The example results of a medium-energy ammonium perchlorate/polyvinyl chloride binder baseline propellant formulation (75/25 mass percentage ratio) have shown that the transient burning rate differs significantly from the steady-state burning rate at the same pressure level.