Modeling slag deposition in the Space Shuttle Solid Rocket Motor

Abstract

The burning of an aluminized propellant within a solid rocket motor produces liquid A1/A12O3 droplets on the propellant surface. Upon leaving the surface and experiencing collisions with other droplets large agglomerates may form. A significant percentage of these droplets and/or agglomerates may be deposited on the inner surfaces of the motor as a consequence of their inability to follow the gas streamlines through the nozzle. The study described herein develops an understanding of this deposition process through flow modeling and the subsequent accumulation and pooling of this slag material within the Space Shuttle solid rocket motor (SRM). From this , an analytical procedure was developed for predicting certain unknowns relating to the deposition and pooling processes. The results of an analysis using this procedure have been qualitatively verified by post-test observations of solidified slag within static horizontally fired motors. The results of the analysis were used to provide an explanation for the slag in the QM-2 and to predict the effects of flight acceleration on slag formation. The procedure is applicable to any rocket motor configuration, although IS was devloped for the SRM.