Early Pulsed Detonation Engine Mishaps

These clips are from a PDE that used a motorized rotary valve fuel injection and a modified automotive ignition system and hand built tungsten electrode spark plugs. The tube i.d. is about 25 mm. The PDE is running on propane and oxygen mixtures. The runs were conducted at 10 Hz. The first video shows the wall material heating up as the engine runs, where some epoxy on the outside catches fire. Next, the force from the detonation waves cause a Shchelkin spiral mounted internally to be ejected out. The spiral was permanently magnetized from the heat during that run.

Category:

Science & Technology

Tags:

• aviation
• pde
• space
• pulse
• detonation
• engine
• combustion

[redsamuraidragon]

Ive been working on a small pulse jet in my garage, along with a small turbine jet.UTA is just right down the street from me. Which classes are most of these engine projects for? This looks like a fun class.

[emb8]

@redsamuraidragon These typically aren't tested as part of a class - mostly research projects conducted by graduate students. You can learn more about what is going on by studying compressible flow and propulsion, which are junior/senior level mechanical and aerospace engineering courses.

[smilingpug]

Agreed. What supersonic craft would be "stealthy" if it left a contrail so dramatic like this? Perhaps this technology should be put on the after .... I mean .... "backburner" and anti-gravity be the propulsion de jour.

[emb8]

If there is a dramatic contrail then the aircraft can presumably just be flown at night.

[smilingpug]

Isn't the PDWE supposed to leave the "string of puffs" as its contrail? One would think this engine would be more erratic.

[emb8]

If you were flying a PDE with a single tube that diverged at the end, the pressure gradient presumably could cause the formation of a vortex ring with each detonation wave. I think this is why the 'string of puffs' and 'donuts on a rope' PDE contrail speculation developed. Although physically plausible, I don't think a single divergent tube engine is a good design. Consequently, I am very skeptical of the contrail pictures online that are supposedly from PDEs.

[unambitious]

Need a fire suppression system and emergency stop button.

[neogastropoda1]

@neogastropoda1 ohhh i just realised its part of the clamp, or is it? lol

[neogastropoda1]

If you dont mind me asking why is epoxy used? it doesnt seem like a good idea as I wouldnt trust using it on my car. im no expert, im just a machinist so i dont really know anything about this stuff.

Would a braised joint or weld be better?

[redsamuraidragon]

@emb8 Ahh... Right on.. Thank you..

[JPK1990]

what are all those hoses there?