|
Abstract:
|
When pressures and temperatures become so high in supersonic flight that it is no longer efficient to slow the oncoming flow to subsonic speeds for combustion , a scramjet (supersonic combustion ramjet ) is used in place of a ramjet . Currently , the transition to supersonic combustion generally occurs at a freestream Mach number around 5 .0 to 6 .0 . This research details analysis completed towards extending scramjet operability to lower Mach numbers , while maintaining performance at higher Mach numbers within the same flowpath as detailed in the Air Force solicitation AF073 -058 . The specific goal is to determine whether the scramjet starting Mach number can be lowered to Mach 3 .50 , and if not , what the constraints are that prohibit it and what the lowest possible starting Mach number for a scramjet is with today's technology . This analysis has produced many significant insights into current and required capabilities for both fuel and overall engine design in lowering the starting Mach number ; these results are presented here . The analysis has shown that a scramjet with a starting Mach number of 3 .50 is not currently possible with the fuels researched unless fuel additives or another addition to the system are used . However , a scramjet with a starting Mach number of 4 .00 is possible with today's existing technology . This paper has designed the engine flowpath for this case ; its specifications and resulting performance are also detailed here . |