Slag accumulation in the titan solid rocket motor upgrade

Abstract

Numerical simulations of slag accumulation in the aft end of the Titan solid rocket motor upgrade (SRMU) are described. These quasisteady, two-phase flow solutions at 0−, 30−, 55−, 80−, 110−, and 125−s burnback geometries involve a gas phase and an A12O3 liquid phase of a single droplet size, where four droplet sizes (10, 35, 60, and 100 fim) have been considered. The two-phase flow calculations are inviscid and rotational (Euler equations), with full momentum and energy coupling between the phases. Both phases are treated with an Eulerian approach. The stability of the AI2O3 droplets with respect to breakup is shown not to affect our predictions. The capture rate as a function of time is determined from the solutions at the five burn times, which is then integrated over the total burn time to determine the total slag captured. It is found that slag capture starts at time zero and continues throughout the firing. Using a droplet size distribution from a recent experimental study produces a total slag accumulation of 2265 kg, which is in good agreement with the static test results. Also, predictions of the slag pool depth as a function of time show good agreement with real-time radiography measurements. Small changes in propellant grain design, such as the use of a short-lived inhibitor in the submerged nozzle region, only provide a small reduction in the total slag captured during the burn. Slag accumulation is unaffected by the g levels typical of an SRMU flight. © 1995 American Institute of Aeronautics and Astronautics, Inc., All rights reserved.