A SCRamjet, or Supersonic Combustion Ramjet, is a propulsive device with no compressor stage or turbine. Like the ramjet, it compresses incoming
air via shock formation and kinetic means as a result of it's own forward speed.
The key difference between a ramjet and scramjet is that the scramjet, as it's
name suggests, may combust a fuel/
air mix at supersonic velocity, whereas a ramjet slows and compresses incoming
air to subsonic velocity before combustion.
The scramjet is useful in the field of hypersonic propulsion systems.