Flow-structural interaction inside a solid rocket motor during ignition transient

Abstract

In this article, a numerical procedure for the analysis of the flow-structural interaction inside a solid rocket motor (SRM) is developed from existing codes. This computer code simultaneously models the developing flowfield and the associated propellant grain deformation during the ignition transient period of SRM operation. It was created by coupling together an ignition-transient flow code, which provides a detailed picture of the time-dependent flowfield and flame spreading inside the motor, with a set of structural influence coefficients, which enable us to calculate the grain deformation that results from a given surface pressure distribution. Also included in the numerical package is a grid-generation code, which generates a grid mesh for the internal-flow passages, based on the deformed shape of the propellant grain. This grid mesh then is used in the ignition transient flow code. As these three component calculations march forward in time, they interact continuously; in this way the flowfield and grain shape are updated continuously. The computer analysis was validated by and used to study the static test failure of the Titan solid rocket motor upgrade (SRMU) that occurred on April 1, 1991 at Edwards Air Force Base. It has since been used to predict the stability of other motors.