A GEOMETRY INDEPENDENT TECHNIQUE FOR SOLID-PROPELLANT GRAIN DESIGN

One of the most important parameters which determines the thrust-time history of a solid propellant rocket is the initial propellant grain s hape and its variation with time. An alternative technique to the pres ently available grain design codes is introduced here which can calcul ate the time evolution of the grain shape for any given initial geomet ry. This technique is based on the volume fraction method which has be en previously used in the modelling of free surface flows. The new tec hnique does not have any restriction on the shape of the grain and is capable of handling any variation in burning rate with time and positi on along the burning surface. This technique is applied to several Bra in types, and the rocket thrust and the internal pressure are calculat ed with time. A power relationship is used to calculate the burning ra te from the internal pressure. Also, the effect of the propellant surf ace curvature on the shape evolution of the grain is discussed.