A Geometry Independent Technique for Solid Propellant Grain Design

Abstract

One of the most important parameters which determines the thrust-time history of a solid propellant rocket is the initial propellant grain shape and its variation with time. An alternative technique to the presently available grain design codes is introduced here which can calculate the time evolution of the grain shape for any given initial geometry. This technique is based on the volume fraction method which has been previously used in the modelling of free surface flows. The new technique does not have any restriction on the shape of the grain and is capable of handling any variation in burning rate with time and position along the burning surface. This technique is applied to several grain types, and the rocket thrust and the internal pressure are calculated with time. A power relationship is used to calculate the burning rate from the internal pressure. Also, the effect of the propellant surface curvature on the shape evolution of the grain is discussed.