Scramjet Combustion Stability Behavior Modeling

A recent breakthrough in combustion stability analysis (UCDS) offers the means to accurately predict the combustion stability of a scramjet. This capability is very important due to the extreme scramjet operational environment, which makes cut-and-try development approaches impractical. With UCDS, it is now possible to accurately predict the scramjet pressure oscillation amplitudes, along with critical parameters, including the unsteady wall heat flux. The UCDS tools were recently applied to the Ares I thrust oscillation issue in support of NASA's Thrust Oscillation Focus Team (TOFT). This effort included the analysis of the Shuttle four segment solid rocket motor (RSRM) to validate the capabilities of UCDS. After analyzing the new five segment (RSRMV) motor being developed for Ares I, GTL used the UCDS insight to identify a relatively minor motor modification that will eliminate the organized motor oscillations. With this validation of the capabilities and effectiveness of UCDS, GTL proposes to extend the application of UCDS by applying it to examine the stability characteristics of a representative scramjet. In addition to predicting the amplitudes of the scramjet pressure oscillations, a UCDS sensitivity analysis will be used to identify critical design parameters and establish development guidelines.