Author Topic: Rotating Detonation Engines  (Read 35029 times)

Offline InterestedEngineer

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Re: Rotating Detonation Engines
« Reply #40 on: 10/15/2022 01:32 am »
But getting back to the issue of engine life vs wear-and-tear, isn't this design inherently going to be more prone to erosion?

We can see that the circular travel of the detonation wave is a cyclical behavior, causing cyclical stresses. Those in turn would lead to more erosion compared to a rocket engine producing thrust under steady-state conditions.

But it does seem to be naturally compatible with the aerospike nozzle.


Nothing the papers referenced by the Japanese paper linked above addresses "erosion" or "wear"

Offline Asteroza

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Re: Rotating Detonation Engines
« Reply #41 on: 01/07/2023 01:58 am »
From our china subforum, CASC ran their RDE recently

https://forum.nasaspaceflight.com/index.php?topic=8447.msg2446756#msg2446756

naming is OHCDRE

but that sometimes shows up as oxygen hydrogen continuous detonation rocket engine
other times oxyhydrogen continuous detonation rocket engine

Best I can find right now

https://www.sinodefenceforum.com/t/chinas-space-program-thread-ii.9003/page-83#post-933362

https://k.sina.com.cn/article_1887344341_707e96d502001c0tg.html

Offline InterestedEngineer

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Re: Rotating Detonation Engines
« Reply #42 on: 01/07/2023 03:47 am »
From our china subforum, CASC ran their RDE recently

https://forum.nasaspaceflight.com/index.php?topic=8447.msg2446756#msg2446756

naming is OHCDRE

but that sometimes shows up as oxygen hydrogen continuous detonation rocket engine
other times oxyhydrogen continuous detonation rocket engine

Best I can find right now

https://www.sinodefenceforum.com/t/chinas-space-program-thread-ii.9003/page-83#post-933362

https://k.sina.com.cn/article_1887344341_707e96d502001c0tg.html

2200 m/sec is half of conventional hydrolox engines.

The flame is yellow, which means it is very fuel rich.

So they have a ways to go.

Offline su27k

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Re: Rotating Detonation Engines
« Reply #43 on: 01/26/2023 04:24 am »
https://twitter.com/NASA_Marshall/status/1618315124447535128

Quote
New rocket engine design, who’s this?

#NASAMarshall propulsion engineers designed the Rotating Detonation Rocket Engine (RDRE) that may one day power both human landers and interplanetary vehicles to deep space destinations!

MORE: https://go.nasa.gov/3WDK2Mp

Offline InterestedEngineer

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Re: Rotating Detonation Engines
« Reply #44 on: 01/26/2023 04:41 am »
https://twitter.com/NASA_Marshall/status/1618315124447535128

Quote
New rocket engine design, who’s this?

#NASAMarshall propulsion engineers designed the Rotating Detonation Rocket Engine (RDRE) that may one day power both human landers and interplanetary vehicles to deep space destinations!

MORE: https://go.nasa.gov/3WDK2Mp

Nice, that looks like fully burned fuel.

Alas, they did not quote exhaust velocity.  They did say the next version was designed to be the one to prove its performance against conventional liquid fuel engines, and at 42 bar I doubt they had very high exhaust velocity, so I think this prototype was there to prove ignitition, shutdown, throttling, and the general operation.

Offline Asteroza

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Re: Rotating Detonation Engines
« Reply #45 on: 01/26/2023 10:48 pm »
https://twitter.com/NASA_Marshall/status/1618315124447535128

Quote
New rocket engine design, who’s this?

#NASAMarshall propulsion engineers designed the Rotating Detonation Rocket Engine (RDRE) that may one day power both human landers and interplanetary vehicles to deep space destinations!

MORE: https://go.nasa.gov/3WDK2Mp

Nice, that looks like fully burned fuel.

Alas, they did not quote exhaust velocity.  They did say the next version was designed to be the one to prove its performance against conventional liquid fuel engines, and at 42 bar I doubt they had very high exhaust velocity, so I think this prototype was there to prove ignitition, shutdown, throttling, and the general operation.

1 minute at 622 psi for 4000 lbs thrust, using a 3D printed engine using GRCop-42 NASA developed copper alloy for 3D printing and high heat transfer.

 10K lbs reusable follow-on being developed from this.

I'm guessing this was a breadboard engine, so external pressure fed. Lots of acoustic fun when someone has to build a turbopump fed RDE...

Offline InterestedEngineer

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Re: Rotating Detonation Engines
« Reply #46 on: 01/27/2023 05:26 am »
1 minute at 622 psi for 4000 lbs thrust, using a 3D printed engine using GRCop-42 NASA developed copper alloy for 3D printing and high heat transfer.

 10K lbs reusable follow-on being developed from this.

I'm guessing this was a breadboard engine, so external pressure fed. Lots of acoustic fun when someone has to build a turbopump fed RDE...

You can get 200 bar tanks, not sure why they limited themselves to 41 bar.

I'd love to sea a Merlin or Raptor turbopump used to feed an RDR.

Offline nicp

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Re: Rotating Detonation Engines
« Reply #47 on: 04/01/2023 05:33 pm »
'Real Engineering" in YouTube has a new video on the rotating detonation engine.



"How NASA Reinvented the Rocket Engine".

EDIT: Oops, this is actually mentioned upthread (the engine, not the video).
« Last Edit: 04/01/2023 05:36 pm by nicp »
For Vectron!

Offline sevenperforce

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Re: Rotating Detonation Engines
« Reply #48 on: 04/06/2023 08:53 pm »
Nice, that looks like fully burned fuel.

Alas, they did not quote exhaust velocity.  They did say the next version was designed to be the one to prove its performance against conventional liquid fuel engines, and at 42 bar I doubt they had very high exhaust velocity, so I think this prototype was there to prove ignitition, shutdown, throttling, and the general operation.

1 minute at 622 psi for 4000 lbs thrust, using a 3D printed engine using GRCop-42 NASA developed copper alloy for 3D printing and high heat transfer.

 10K lbs reusable follow-on being developed from this.

I'm guessing this was a breadboard engine, so external pressure fed. Lots of acoustic fun when someone has to build a turbopump fed RDE...
Isn't one of the advantages of RDEs that they are essentially self-pressurizing so you don't need high inlet pressure? Or am I way off base?

Offline Asteroza

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Re: Rotating Detonation Engines
« Reply #49 on: 04/09/2023 11:00 pm »
Nice, that looks like fully burned fuel.

Alas, they did not quote exhaust velocity.  They did say the next version was designed to be the one to prove its performance against conventional liquid fuel engines, and at 42 bar I doubt they had very high exhaust velocity, so I think this prototype was there to prove ignitition, shutdown, throttling, and the general operation.

1 minute at 622 psi for 4000 lbs thrust, using a 3D printed engine using GRCop-42 NASA developed copper alloy for 3D printing and high heat transfer.

 10K lbs reusable follow-on being developed from this.

I'm guessing this was a breadboard engine, so external pressure fed. Lots of acoustic fun when someone has to build a turbopump fed RDE...
Isn't one of the advantages of RDEs that they are essentially self-pressurizing so you don't need high inlet pressure? Or am I way off base?

Still gotta inject sufficient oxidizer and fuel before the next shockwave arrives at that point in the annulus, so the time constraint points to fairly high injection pressure. Plus you gotta wait a bit after the shock passes for the exhaust to cool sufficiently to not autoignite the next round of propellants you just injected, so that further constrains injection time. How the injection is implemented might matter to, such as a ring of individual injectors in an annular plate.

Offline sanman

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Re: Rotating Detonation Engines
« Reply #50 on: 05/30/2023 05:12 am »
If a single engine of this type were to be used on a launch vehicle, or on a lander, then is there any possibility/danger of it introducing an axial roll? Or would you need to have pairs of these engines with the detonation waves moving in opposite directions to cancel out any rotational torque?
« Last Edit: 05/30/2023 05:55 am by sanman »

Offline sevenperforce

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Re: Rotating Detonation Engines
« Reply #51 on: 05/30/2023 02:06 pm »
If a single engine of this type were to be used on a launch vehicle, or on a lander, then is there any possibility/danger of it introducing an axial roll? Or would you need to have pairs of these engines with the detonation waves moving in opposite directions to cancel out any rotational torque?
I don't believe there would be any likelihood of significant axial roll inducement from a RDE. If there was any roll at all -- which I don't think is the case -- it would be well within the authority of whatever roll control mechanism the vehicle otherwise had.

Think of it less like something that's actually rotating and more like a ring of tiny thrust chambers around an annular aerospike engine, with each thrust chamber firing in pulses. The location of the thrust moves in a circle around the engine but the thrust is still occurring in the forward direction.

Offline sanman

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Re: Rotating Detonation Engines
« Reply #52 on: 05/30/2023 02:43 pm »
I don't believe there would be any likelihood of significant axial roll inducement from a RDE. If there was any roll at all -- which I don't think is the case -- it would be well within the authority of whatever roll control mechanism the vehicle otherwise had.

Think of it less like something that's actually rotating and more like a ring of tiny thrust chambers around an annular aerospike engine, with each thrust chamber firing in pulses. The location of the thrust moves in a circle around the engine but the thrust is still occurring in the forward direction.

So you're saying that all thrust is directed entirely downward/axially, and no component of the thrust is directed laterally(tangentially to the circumference in this case)? Or are you saying that the lateral components cancel?

This thing uses a traveling combustion wavefront, whose supersonic travel velocity is the basis for the super-efficient constant-volume combustion. Given that the wavefront is propagating around that circular loop at supersonic travel velocity, and thus in a particular direction around the central axis, why is that going to be benign and neutral to overall angular momentum?
It just seems like this loop velocity would cause some effects in free-flight.
« Last Edit: 05/30/2023 02:44 pm by sanman »

Offline sevenperforce

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Re: Rotating Detonation Engines
« Reply #53 on: 05/30/2023 03:23 pm »
I don't believe there would be any likelihood of significant axial roll inducement from a RDE. If there was any roll at all -- which I don't think is the case -- it would be well within the authority of whatever roll control mechanism the vehicle otherwise had.

Think of it less like something that's actually rotating and more like a ring of tiny thrust chambers around an annular aerospike engine, with each thrust chamber firing in pulses. The location of the thrust moves in a circle around the engine but the thrust is still occurring in the forward direction.

So you're saying that all thrust is directed entirely downward/axially, and no component of the thrust is directed laterally(tangentially to the circumference in this case)? Or are you saying that the lateral components cancel?

This thing uses a traveling combustion wavefront, whose supersonic travel velocity is the basis for the super-efficient constant-volume combustion. Given that the wavefront is propagating around that circular loop at supersonic travel velocity, and thus in a particular direction around the central axis, why is that going to be benign and neutral to overall angular momentum?
It just seems like this loop velocity would cause some effects in free-flight.
Keep in mind that the "thing" traveling around in a circular loop is a pressure wave, not an actual propellant flow. The thrust from detonation is at least almost entirely, if not truly entirely, directed axially.

If a substantial component of the detonation thrust was being directed laterally/circumferentially, then the engine would suffer from significant cosine losses and thus could not be nearly as efficient as claimed.

With constructive and destructive wave interference you can create a standing wave in a cylindrical system which hovers in place, moves in one direction, or moves in the other direction, all with negligible (if any) rotational torque being applied to the vessel itself.

Offline sanman

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Re: Rotating Detonation Engines
« Reply #54 on: 05/30/2023 04:48 pm »
Keep in mind that the "thing" traveling around in a circular loop is a pressure wave, not an actual propellant flow. The thrust from detonation is at least almost entirely, if not truly entirely, directed axially.

If a substantial component of the detonation thrust was being directed laterally/circumferentially, then the engine would suffer from significant cosine losses and thus could not be nearly as efficient as claimed.

With constructive and destructive wave interference you can create a standing wave in a cylindrical system which hovers in place, moves in one direction, or moves in the other direction, all with negligible (if any) rotational torque being applied to the vessel itself.

Thanks for your explanation. So can standing wave potentially be exploited to provide any roll control?

Also, constructive/destructive interference means addition/subtraction of pressure in the pressure wave, which then affects combustion efficiency. So by fiddling around with the wave pattern, aren't you then affecting your overall thrust output?

Furthermore, can the changing of the standing wave distribution/pattern then be used to provide steering, by deviating from axisymmetric thrust distribution?

Offline sevenperforce

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Re: Rotating Detonation Engines
« Reply #55 on: 05/30/2023 05:45 pm »
Keep in mind that the "thing" traveling around in a circular loop is a pressure wave, not an actual propellant flow. The thrust from detonation is at least almost entirely, if not truly entirely, directed axially.

With constructive and destructive wave interference you can create a standing wave in a cylindrical system which hovers in place, moves in one direction, or moves in the other direction, all with negligible (if any) rotational torque being applied to the vessel itself.

Thanks for your explanation. So can standing wave potentially be exploited to provide any roll control?

Also, constructive/destructive interference means addition/subtraction of pressure in the pressure wave, which then affects combustion efficiency. So by fiddling around with the wave pattern, aren't you then affecting your overall thrust output?

Furthermore, can the changing of the standing wave distribution/pattern then be used to provide steering, by deviating from axisymmetric thrust distribution?
Sorry if I was misleading. The example of a standing wave was to illustrate how the motion of pressure waves in a cylinder can be made independent of any torque on that cylinder, not to suggest that an RDE engine uses actively-controlled constructive interference to create standing waves.

I suppose you could characterize the overall thrust graident itself as a standing wave but that's getting overly abstract.

Online edzieba

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Re: Rotating Detonation Engines
« Reply #56 on: 05/31/2023 06:44 am »
Keep in mind that the "thing" traveling around in a circular loop is a pressure wave, not an actual propellant flow. The thrust from detonation is at least almost entirely, if not truly entirely, directed axially.

If a substantial component of the detonation thrust was being directed laterally/circumferentially, then the engine would suffer from significant cosine losses and thus could not be nearly as efficient as claimed.

With constructive and destructive wave interference you can create a standing wave in a cylindrical system which hovers in place, moves in one direction, or moves in the other direction, all with negligible (if any) rotational torque being applied to the vessel itself.

Thanks for your explanation. So can standing wave potentially be exploited to provide any roll control?

Also, constructive/destructive interference means addition/subtraction of pressure in the pressure wave, which then affects combustion efficiency. So by fiddling around with the wave pattern, aren't you then affecting your overall thrust output?

Furthermore, can the changing of the standing wave distribution/pattern then be used to provide steering, by deviating from axisymmetric thrust distribution?
One of the biggest challenges in getting and RDE working at all is keeping the detonation wave stable. Attempting to introduce asymmetry or periodicity is more likely to cause the engine to fail (possibly destructively) than introduce off-axis combustion vs. the known effective technique of gimbaling the engine.

Offline Asteroza

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Re: Rotating Detonation Engines
« Reply #57 on: 10/01/2023 10:47 pm »
More chinese  RDE progress (kerosene or H2, which is it really?)

twitter.com/cnspaceflight/status/1707551774708773005

Quote
TWR-ENGINE recently conducted the first hot fire test of a 1000N-thrust kerosene fueled rotating detonation engine, H2.

https://twitter.com/cnspaceflight/status/1707552373458280658

Quote
A photo of the RDE. They have more of different thrusts
« Last Edit: 10/02/2023 05:55 am by Asteroza »

Offline RON_P

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Re: Rotating Detonation Engines
« Reply #58 on: 10/05/2023 12:00 pm »
RTX ( Raytheon ) to develop rotating detonation engines for DARPA

https://www.rtx.com/news/news-center/2023/10/04/rtx-to-develop-rotating-detonation-engine-for-darpa?utm_source=twitter&utm_medium=organic&utm_campaign=D22&utm_content=_&utm_id=1148384647911483846494138&linkId=239291744
Quote
TUCSON, Ariz., Oct. 4, 2023 /PRNewswire/ -- Raytheon, an RTX (NYSE: RTX) business, has received a contract from the Defense Advanced Research Projects Agency (DARPA) to develop Gambit, an air-breathing propulsion demonstration program that uses a novel rotating detonation engine. This type of engine is more compact, provides a higher efficiency propulsion source than conventional missile propulsion and offers the potential for lower costs.

Gambit is a first-of-its-kind engine development program that could support future weapons systems for multiple military services. The compact nature of the engine and its efficient combustion provide a boost in range and speed relative to current long-range weapons, allowing the ability to quickly respond to advanced threats.

"This is a revolutionary propulsion system," said Colin Whelan, president of Advanced Technology at Raytheon. "We're leveraging existing digital design tools and experience from across the entire RTX business to rapidly prototype this next-generation strike weapon and mature the technology."

Under the contract, RTX will rely heavily on iterative development of performance models which will be anchored by real-world data from incremental system tests. This proven method accelerates learning to provide more certain flight test outcomes, saving both time and cost. Future optional phases of the Gambit program will shift to building hardware to conduct a flight weight free-jet test.

With this contract, RTX becomes the first company to apply rotating detonation engine technology into an actual test system.
« Last Edit: 10/05/2023 12:36 pm by RON_P »

Offline InterestedEngineer

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Re: Rotating Detonation Engines
« Reply #59 on: 10/06/2023 02:44 am »
Under the contract, RTX will rely heavily on iterative development of performance models which will be anchored by real-world data from incremental system tests. This proven method accelerates learning to provide more certain flight test outcomes, saving both time and cost. Future optional phases of the Gambit program will shift to building hardware to conduct a flight weight free-jet test.

Also proven to boost profits.

And modeling, as Elon shows, makes you learn nothing about how to build these systems in volume.  Which means the unit cost will be insanely high.

You need to build iterate, not model iterate

 

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