Historical Survey on Enhanced Mixing in Scramjet Engines

Select methods are reviewed that have been used by the scramjet community to enhance mixing of fuel with oxidizer to achieve high combustion efficiency with reduced length combustors. The review also includes research on enhanced supersonic free shear layer mixing from the jet noise reduction community. This latter community has considered concepts involving acoustic excitation or passive excitation of shear layer instabilities to minimize noise production. Several of these concepts are amendable to active control for system optimization. (Author)