Solid rocket motor internal flow during ignition

Abstract

A numerical procedure is presented for the analysis of the internal flow in a solid rocket motor (SRM) during the ignition transient period of operation, along with the results obtained when this computer code was applied to several motors. The purpose of this code development effort was to achieve a detailed picture of the unsteady flowfield for a SRM of arbitrary design during this period of ignition delay, propellant ignition, flame spreading, and chamber filling/pressurization. The approach was to combine an unsteady, axisymmetric solution of the equations of inviscid fluid motion (Euler equations) with simple models for the convective and radiative heat transfer to the propellant surface during the run up to ignition. An unsteady, one-dimensional heat conduction solution for the propellant grain is coupled to this unsteady flow solution in order to calculate the propellant surface temperature. This solution, together with a surface temperature ignition criterion, determines the ignition delay and flame spreading. First, data were used from a Titan 5-1/2-segment solid rocket motor static firing to fix an unknown constant in the heat transfer model. Then, the computer code was applied to two solid rocket motors, Titan 7-segment and Space Shuttle, for which time-dependent chamber pressure measurements weremore » available from static firings. Good agreement with the data was obtained. 17 refs.« less