Scramjet Combustion Stability Behavior Modeling

A recent breakthrough in combustion stability analysis (UCDS) offers the potential to 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 will be 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). After validating the UCDS capabilities by analyzing the RSRM, GTL applied the tool to identify a relatively minor motor modification that should eliminate the organized motor oscillations. Building upon this validation, GTL took the first step towards extending UCDS to scramjets in the Phase I effort. While a variety of issues and challenges were uncovered during the effort, the effort confirmed that the UCDS framework is fully applicable to scramjets. However, the effort also revealed that the DCR scramjet is far more complicated and difficult to analyze than a typical rockets. In the Phase II effort, GTL proposes to address the key issues that were identified during the Phase I effort.