This is a form of jet engine that is able to operate at hypersonic (mach 5+) speeds. Very similar in operation to the notorious pulsejet engine used in the Nazi's V1 buzzbomb, a pulse-wave engine creates thrust though a series of very rapid explosions instead of the steady burn of a traditional turbojet engine.

At high mach numbers, the air behaves differently than at lower speeds. A traditional jet would literally be "blown out" like a candle by the passage of high-speed air through it, if the shock wave from the front of the aircraft let any air into the engine at all.

The reason that a pulse-wave-detonation-powered aircraft is suited for extremely high speeds is twofold. Since the engine closes itself off during each pulse, the explosion is not disrupted from incoming air. Second, in such an aircraft, the entire body of the plane forms the intake for the engine, with the nose shaped in a way that slows the hypersonic air the vehicle is ploughing through enough that it can enter the engine smoothly. The rear of the aircraft is also specially shaped to control the exhaust plume. The engine "fires" at pulse rates of around 100 times per second, producing nearly continuous thrust.

This method of propulsion is what many believe powers the secret/imaginary aerospace spyplane Aurora, the fabled replacement to the venerable SR-71. Many believers point to mysterious "donuts on a rope" contrails near Groom Lake (also called Dreamland, and linked to Area 51), where the Air Forces tests its latest aircraft as evidence of the pulsing exhaust of the Aurora.
