Internal flow analysis of large L/D solid rocket motors

Abstract

Traditionally, Solid Rocket Motor (SRM) internal ballistic performance has been analyzed and predicted with either zero-dimensional (volume filling) codes or one-dimensional ballistics codes. One dimensional simulation of SRM performance is only necessary for ignition modeling, or for motors that have large length to port diameter ratios which exhibit an axial "pressure drop" during the early bum times. This type of prediction works quite well for many types of motors, however, when motor aspect ratios get large, and port to throat ratios get closer to one, nvo dimensional effects can become significant.The initial propellant grain configuration for the Space Shuttle Reusable Solid Rocket Motor (RSRM) was analyzed with 2-D, steady, axi-symmetric computational fluid dynamics (CFD). The results of the CFD analysis show that the steady-state performance prediction at the initial bum geometry, in general, agrees well with I-D transient prediction results at an early time, however, significant features of the 2-D flow are captured with the CFD results that would otherwise go unnoticed. Capturing these subtle differences gives a greater confidence to modeling accuracy, and additional insight with which to model secondary internal flow effects like erosive burning.

Convective Heat Transfer in the Reusable Solid Rocket Motor of the Space Transportation System

“…This analysis was performed to maintain a continuity with previous analyses [3][4][5][6][7][8] of this motor; serve as a non-vectored baseline for any three-dimensional vectored nozzles; provide a relatively simple application and test for various CFD solution schemes, grid sensitivity studies, and turbulence heat transfer/modeling; and calculate the nozzle convective heat transfer coefficients. The purpose of this study was to determine the convective heat transfer in the RSRM.…”

“…This slag layer then sheared from the nozzle cowl/boot ring surface and impacted the aft dome case insulation at the location where the greatest erosion occurred. Fourth, Laubacher [6] conducted a two-dimensional axisymmetric analysis to compute chamber pressure drop in the RSRM. The walls were assumed to be adiabatic and he utilized the standard κ − ε turbulence model and heat transfer engineering vol.…”