Aerospace Engines A to Z
Aerospace Engines A to Z

Updated: 16-Mar-2021

PDE (Pulse Detonation Engine)


PDE stands for Pulse-Detonation-Engine, a new propulsion system that uses the principle of pulse jets but instead of combustion by deflagration (vigorous combustion), in PDEs this combustion occurs by detonation of the mixture.

-Detonation is a more powerful reaction reaching higher pressures and supersonic exhaust velocities.

Running PDE
“Running PDE”

From Appendix 6: Pulse Detonation Engines are also called “Pulse Detonation Wave Engines”.

-This is how the PDWE now appears for a hypersonic vehicle capable of reaching Mach 10 at high altitudes, as much as 180,000 feet.

Exterior appearance of a future PDWE
"Exterior appearance of a future PDWE"

-At least the one proposed in this image is planned to run on liquid methane.

-The idea is to take spaceships to the edge of the atmosphere (and the beginning of space) where rocket-type engines would be activated.

-In several tests with engines of this type, as the detonation is pulsating, the characteristic steam traces behind the vehicle have been observed, similar to a string of donuts strung on a rope.

-In other words, a few steamed crowns and inside a continuous line of steam.

-Pulse detonation engines or PDE are conduits in which combustion occurs as detonation with the exhaust exiting at speeds higher than sound, even producing shock waves.

-Tests are made continuously like the in the case of General Electric.

-It gives a noisy and furious thrust, so perhaps it is only suitable for remote areas from population or at very high altitudes.

GE PDE-type test engine
“GE PDE-type test engine”

-There are projects to combine the high operation speed of PDE engines in upcoming aircraft.

-To do this, the subsonic operation must be combined with the supersonic one.

-One of the solutions are hybrid turbofans, as is the below example.

Turbofan-PDE hybrid
"Turbofan-PDE hybrid”

-A crown of PDE tubes are placed in the By-pass duct to start operating at its time.

From Appendix 6: A Pulse Detonation Engine (PDE) has been tested in a demonstration test at the Texas University in the city of Arlington. (see main text).

PDE in Texas
“PDE in Texas” (photo W. Commons)

-Another PDE, presented in one of the EAA Air Adventure exhibitions and installed on a Long-ez is the one shown below.

PDE exhibited at an EAA event
“PDE exhibited at an EAA event”

-The studies have been carried out at Caltech, or California Institute of Technology.

PDE with air intake, cutaway
“PDE with air intake, cutaway” (PiP)

-There are also models to study the displacement of waves and loads inside the engine, as well as their amplitude.

Computer study of PDE behavior
“Computer study of PDE behavior” (PiP)

PDE air-intake schematic
“PDE air-intake schematic”

Long E-Z powered by PDE
“Long E-Z powered by PDE”

From Appendix 9: Initials of “Pulse Detonation Engines” (see main text). On a recent visit this end of the year (2013) to the USAF Museum in Dayton, we found the Vari-Ez plane with this engine and one placed next to it on display.

PDE in front of the Vari-Ez
“PDE in front of the Vari-Ez”

-The PDE has four combustion chambers and four tailpipes of a suitable length.

-It turns out that its appearance seems to us like that of a sports car engine, seen from above.

Looks like cylinder heads and turbo
“Looks like cylinder heads and turbo”

PDE exhibition panel
“PDE exhibition panel”


1-The intake valve opens (fuel and air fill the detonation tube).

2-The intake valve closes and it is ready for ignition).

3-Ignition, followed by deflagration as subsonic combustion, and then followed by a transition to detonation (explosion).

4- The detonation flows at Mach 5 through the detonation tubes.

5-The exhaust valve opens purging the chamber, the gases go towards the turbo and when the intake valve is opened again, the fresh mixture prepares the next cycle.

-In a way, the author recalls Lorin's engine.

Lorin's primitive pulse engine
"Primitive Lorin Pulse Engine"

From Appendix 10: In Russia, Pulse Detonating engines, such as the one in the figure below, have also been tested.

Russian PDE
“Russian PDE”

-PDE is "Pulse Detonant Engine" something like a pulse jet but higher frequency, as much as 200 pulses per second.

-In that country they are called PuVRD.

Model: Pulse Detonantion Wave Engines

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Model: Pulse-detonation-engines

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