What Is A Rotating Detonation Engine - And Why Are They Better Than Regular Engines

There's been a few stories recently about detonation engines and how they're supposed to be superior to traditional jet or rocket engines. So, what is a detonation engine, what's the difference between a pulsed and rotating engine and why does thermodynamics predict these are better than traditional engine designs.

[lunaticseclipse]

He didnt tell me thats he's scott manley and to fly safe at the end.
I feel lost.

[Nick-qxno]

Now i am wondering if i have to fly safe or not....

this world is full of uncertainties....

[AndreiKucharavy]

"I don't have any rocket engines in my garden"
- totally what someone with rocket engines in their garden would say.

[blurglide]

I helped build the first self-aspirating Pulsed Detonation Engine with Dr. Fred Schauer at Air Force Research Laboratory in 2003. It was built with junkyard parts (An old Honda motorcycle engine with the tubes jutting out between the block and head), but proved the concept. They made another non-self-aspirating PDE (it had a supercharger powered with a piston engine) that actually powered a Long-EZ in flight several years I left the program, which is the one you see at 3:50 in the video. You're just seeing the PDE there- the big compressor in the belly tank that fed it. I still have my engineering-pad sketches of a variety of rotating PDEs, except my ideas would have one wall of the tube rotate, or have the tubes rotate more like a gatling gun.

[MillionFoul]

You know, it's kind of funny: I'm taking a break from my thermo class to watch this video, and this video is half ideal heat engines!

[chicoliu]

It feels weird that you don’t wish us fly safe at the end of the video

[HydraulicPressChannel]

Edit: I already forgot but seems that we also filmed rotating explosion with oxy-acetylene bubbles :D Just one lap but still. It's on end of the same video

[thebigboss]

As a PhD student researching combustion and detonation processes, I’m very impressed by how intuitively you explained the differences between the two. Great video!

[SupernovaSpence]

"Anyways, I'm Scott Manley! FLY SAFE!"

WE MISSED YOUR OUTRO! 😕

[vishnuvishnuprful]

• RDE’s need a single initiation for operation and the combustion is self-sustained. The detonation waves will stabilize in a short duration.
• Frequency of operation is of the order of KHz. Which makes uniform exhaust flow downstream of the combustor.
• Compared to PDE’s the thrust produced by an RDE is continuous. The detonation waves are enclosed inside the channel which reduces the energy lose with exhaust. Which makes it a suitable replacement for the gas turbine combustor.
• The reactant inflow does not require any flapping valves as well as it is a self-pressurizing system. The injection pressure loss will be overcome by pressure gain combustion. So it is easy to integrate it with an axial compressor with lesser number of stages.
• RDE’s have very high power density, so that the size of the combustor reduces drastically.
• Smaller the size of the combustor, smaller will be the losses due to wall heat transfer. Moreover, the exhaust flow can be simply approximated to a 1D quasi steady flow.
• It is easy to resize the combustor because there isn’t any hard rule for the size constraints.
• Fuel injection system associated with such combustors are fairly simple, as they don’t need any moving parts or swirlers.
• Integration with an existing turbine stage will be easy because of lower unsteady pressure fluctuations downstream of a properly designed RDE combustor.
• Propagation of the detonation wave independent of direction of inflow and outflow of reactants and products respectively. Such combustor can be easily integrated to axial as well as centrifugal compressors.
• Even though there is no need of a secondary air for dilution of exhaust, if employed it will further reduce the periodic oscillations downstream of the combustor.
• RDE’s possess large effective thrust, which is a measure of how well the total pressure of reactants are converted to thrust. So an engine employed with RDE combustor can work with lesser number of compressor stages compared to the same system with a constant pressure combustors.
• Large specific thrust and high Specific impulse of the system make sure the maximum utilization of the available air.
• Operating space (mass flow rate of reactants vs equivalence ratio) is wide for an RDE combustor. So it can be effectively operated with equivalence ratios required for low emissions.
• Most preferable reactants which can be initiated are H2 and O2 combination. So having a clean combustion is favored with such combustors.
• The mode control is not well defined as of now and there are scope of having multiple co rotating detonation propagation can improve the capabilities of this combustor.

[darioinfini]

I've got a flight to catch in the morning and I feel very nervous after the end of this video...

[phoephoe]

4:14
You do realise you've just challenged Colin Furze to build a supersonic pulsed-detonation engine....

(this is gonna be awesome)

[novikovPrinciple]

... so you're telling me I can put an explosive device that rotates under my Kerbals?

[CarlJohnson-xzrs]

I'm confused as to who teaches me about rocket science after the video ended.

[dmitryincog]

You videos strike a perfect balance between hardcore science and a pop sci. It's super hard to explain such complex topics without degrading into totally handwavy talks. And it involves very good understanding of the subject. I can't even imagine how much researching do you put in.
Youtube is a better place thanks to you! Thank you :)

Already watched this before, but now it's time for a refresh.

[RebeccaSmith-yyyi]

Dang, I forgot and just crashed my plane.

[MushVPeets]

I guess there's no flying safe with a literal detonation constantly under your rear end.

[pawelrek]

Scott, take a look at work of Jan Kindracki from Warsaw University of Technology, Poland. This guy is was recently taking care of applying a RD into an old Russian turbine engine (GTD-350) to prove a concept. Jan is great teacher (during our studies we had some lectures about RDE to better understand it) and he's really responsive. As far as I remember he was able to sustain a detonation in a relatively small rocket engine (100-200N?) for 10+ seconds if I remember correctly. Awesome dude and his lab even better. Don't quote me on numbers - it was years ago.

[Garryck-]

So who else is here now that Japan has actually flown a RDE?