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Pulse Detonation Engines: The Future of Aviation
noah_fense writes "Popular Science is running an interesting article about the race to replace the jet turbine with a more efficient source of Mach-breaking airpower: the pulse-detonation engine. It works by detonating (instead of slow burning) fuel hundreds to thousands of times a second. PDE technology is poised to make supersonic passenger flights and space travel affordable. 'Pulse detonation is a hot topic in combustion research,' says Gabriel Roy of the Office of Naval Research. 'Compared with gas turbines, the PDE has a much simpler configuration. It has the capability of going from subsonic to supersonic using less fuel, and it's thermodynamically more efficient. But there are big engineering issues--thermal fatigue, noise. It's very challenging research.'"
I think that several such paradigm shift in several disciplines must occur in order to keep space exploration viable in the near future. I am always impressed by the near-wishful thinking that MUST occur before science leaps forward. Plus, they're competing for juicy government contracts, and that always greases the wheel.
Windows XP SP2 told me to install third-party software that prevents viruses and protects stability... I chose Ubuntu
The article discusses using thrust pulses from combustible propellant, not the nuclear explosions of scifi lore.
I remember studying this in college back in the 80s. It was still mostly theoretical then. despite the amount of research that had gone into it. The main problem back then seemed to be fine control of fuel delivery, ignition and monitoring of the results. Computer control seems to have solved at least part of that. It looks like, from the article, that precision machining and hightemp materials might have solved some of he other ones problems.
;)
Hell, maybe I'll make it to space after all.
If they can really make this work, real-world, it might revolutionize high-altititude to orbit engines. It's probably at least a decade away from production use, but still....
Utterly cool. Cut off not their research funds!
realityshunt
Democracy is susceptible to being led astray by having scapegoats paraded in front of the electorate.
Actually it looks like it is intended for 10,000 different things, whatever might make some investors ees flash green. Like all new technologies, you promise they can solve all the world's ails to get development money, then you end up applying your research to a few narrow fields in the real world at the end.
11*43+456^2
Some of his ideas certinaly do sound like quackery.
BUT
Some of the quackiest ideas were built, photographed and demonstrated.
I dont get how he is dismissed as a quack so often. Im sure something called a death ray dindt help, but he never invented something he couldnt demonstrate. Considering he is one of the fathers of the era you live in now (much more than edison) you should give him some more credit.
It's easier to fight for one's principles than to live up to them.
A key factor was mentioned here: pulsejets are REALLY loud. So if we end up with a bunch of them flying around, where exactly will they be taking off and landing. Because airports in urban areas already have severe noise problems.
Maybe you know more about PDEs than I do, but everything I've read on ACTUAL engines show much lower efficiency for PDEs than either turbojets or Ramjets. There seems to be a midrange where they are competitive, but for >Mach 2.3 for Ramjets and Compression ratios greater than 4 in turbojets, PDEs lose out.
PDEs have two major advantages:
They're simple, which means if you only want to use it once, the cost is potentially lower than a turbojet, and there are fewer ways in which it can fail.
You can pump in a lot of fuel, even above stoichiometric, to get large thrusts at the expense of efficiency.
PDEs have great potential, but they're a long way from challenging either turbojets or ramjets yet.
Tony.
1. A gas turbine is an IC engine.
2. Various IC piston engines have successfully been converted to operate reliably with hydrogen decades ago.
3. Although H2 permits high compression ratios, it does not require them. The same applies to LPG.
4. The main obstacle is therefore not satisfactory engine operation, but the hydrogen infrastructure.
Are you actually trying to propose this as a new theory, or did you read it somewhere else and are pretending to have come up with it? I have never read a description of the "donuts on a rope" contrail without an accompanying description of pulse jets, and the connection is incredibly obvious.
And why is this type of contrail "infamous"?
IIRC, Ethylene oxide and oxygen are the primary ingredients in the fuel-air bomb. So, yeah, I would expect the equivalent of an open-ended bomb to produce more thrust than a conventional jet engine. I'll be more impressed when they can do this without supplemental oxygen, bomb fuel, and a large compressor to "simulate mach 4 speeds".
Granted, it sounds promising, but as of yet they haven't managed to build a prototype which can run on conventional fuels (hydrocarbon based, ethyl alcohol, etc...). Furthermore, the article states that these engine may someday produce power from near standstill to hypersonic speeds, yet their prototype can't run at less than mach4, and requires supplemental O2 at that. Quite frankly, the ramjet designs of the 80's showed more promise than PDEs.
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Our materials technology currently lags too far behind current levels of commercial flight tech. As long as "metal fatigue" can be used as an explanation or even part of an explanation for something going wrong in any field of human endeavour we should all be keeping our feet firmly on the ground.
kartune85 : Incapable of reason, observation or learning. A kind of dim, drab, flightless parrot.
DOH!!
Remember kids, don't drink and post.
Forget thrust, drag, lift and weight. Airplanes fly because of money.
If you actually pick up a copy of Popular Science and read the article, they talk about making a "hybrid" system-- pulse detonation coupled with a regular jet (as found on 747's, etc.) The pulse detonation would occur on the outside of the turbines, where some fuel is wasted. The fuel is simply detonated again, providing even more power for your buck. I'm sure the noise level would be negligible, especially once one is up in the air.
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