A Grain Burnback Analysis Model for Solid Rocket Motor Preliminary Design

Abstract

In many space applications, Solid Rocket Motors (SRM) with different thrust-time profiles are required according to the characteristics of the mission. For a given propellant chemical composition the main parameter affecting the thrust-time profile is the grain geometry. Grain burnback analysis is the determination of the change in the grain geometry during operation of the motor. In this project a new mathematical model to perform this kind of analysis has been developed and later implemented within a MATLAB® environment with the purpose of providing a fast and accurate tool which can be coupled with the ballistic solver SRP in order to predict the performance of SRMs. The model is based on the numerical drafting technique developed by Peterson et al (1968). The initial grain geometry is reproduced using several input figures in various combinations. The burning simulation is performed by shifting the contours of the figures representing the web. Simulation is accomplished using four basic figures, namely a right prism, a right cylinder/cone, a torus and a sphere. Propellant area at each cross section along the grain axis is computed using the intersection between these figures and the cross plane. Propellant volume is calculated by integrating the propellant area along the grain axis. The graphical and numerical results obtained indicate that the implemented tool is suitable for the preliminary design of a solid rocket motor for many different examined geometries.