Certain analysis of a solid rocket motor (SRM) with modified pentagonal grain configuration

Abstract

Solid propellant rocket motors (SRMs) have wide range of usage in satellite launchers. SRM uses solid propellant grains with different types of perforations. Usage of perforations with cornered shapes (i.e., square, rectangle, pentagon etc.) results in higher burning rate which results in sudden decrease of chamber pressure (or thrust). Since change of state of burning is not desirable, these kinds of perforations cannot be used for SRMs. Better reduction in burning rate can be achieved by changing the geometrical configuration of these shapes which enables the usage of cornered shapes as grain perforations in SRMs. Design and analysis of grain configurations with number of web steps can be used as tool for predicting the performance of rocket motors. Burn back steps of the grain can be predicted for required intervals of time by 2D design using CATIA. In this study, burn back steps of 3D grains with different types of pentagonal configuration perforations was investigated. For each web step, a 3D model was prepared and a required performance characteristic was obtained using analytical calculations. CFD simulation of the 3D grain was done in ANSYS (FLUENT) to assure the validity of the grain geometry of SRM. Various types of CFD models were used for CFD simulation in the field of SRM in this study, standard k-ɛ model is used for simulation purpose.