Burning Regression Analysis for 3D Grain Configurations

Grain design is essentially filling a prescribed volume (chamber case) with a certain shape of propellant so as to ensure mission requirements. An infinite number of possibilities exist, covering from two dimensional to three dimensional grain designs. Accurate calculation of grain geometrical properties plays a vital role in performance prediction. In this paper a methodology has been presented for designing 3D grain configuration for Solid Rocket Motors (SRMs). The design process involves parametric modeling of the geometry in CAD software through dynamic variables that define the complex configuration. Initial geometry is defined in the form of a surface which defines the grain configuration. Grain burn back is achieved by making new surfaces at each web increment and calculating geometrical properties at each step. Geometrical calculations are based on volume and change in volume calculations. Models for axisymetric and finocyl grain configuration have been developed. Equilibrium pressure method is used to calculate the internal ballistics. The procedure adopted can be applied to any complex geometry in a relatively simple way for preliminary designing of grain configuration.