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Ramjet with Levitating Compressor wheel

Uses electromagnetic to levitate a compressor wheel
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I'm sure you've all seen the magnelev toy. Well why not use a magnetically levitating compressor wheel on a Ramjet. I mean it will elininate the need to carry oil and increase the efficiency of the engines power output
SIVOLC, Jul 12 2004

High Temperature Magnetic Bearings for Gas Turbines http://www.grc.nasa...5000/5930kascak.htm
Nasa work from a decade ago [lurch, Mar 02 2008]

LEVITRON® - The Amazing Anti-Gravity Top http://www.levitron.com/
the magnelev toy? [baconbrain, Mar 02 2008]

[link]






       <ob> Roger that <ob>
skinflaps, Jul 12 2004
  

       You're talking about magnetic bearings, then?
RayfordSteele, Jul 12 2004
  

       Since a ramjet has no compressor wheel, I'm sure it doesn't matter much what you levitate it with. Stick it to the top of the cockpit with chewing gum, if you like.
lurch, Jul 12 2004
  

       What lurch said. By its very design, a ramjet needs no compressor. Magnetic bearings do exist, though.
david_scothern, Jul 13 2004
  

       I'm not getting it, either. Is this just a joke? Anyone else?
jutta, Mar 01 2008
  

       I don't think it's a joke - I think he/she is thinking of a different type of engine (maybe a conventional jet?), and proposing magnetic bearings for the fans.
MaxwellBuchanan, Mar 01 2008
  

       I agree [MB]. But the toy and the magnetic bearings needed for a compressor wheel have many differences, and not just in size. I'm rating this as "magic magnets", by someone not very technical.
baconbrain, Mar 02 2008
  

       This is a classic example of amateur stream of consciousness engeneering. Use technical words to try to mate two technologies that you don't understand to "increase efficiency, power output". This is is epitomized by bastard perpetual motion machines: Somehow there is a combination of technologies that can "increase efficiency, power output" to more than 100%.
WcW, Mar 02 2008
  

       So, [bacon] and [WcW], based on lurch's link, should this be MFDd on the grounds of its being magic, or being baked?
MaxwellBuchanan, Mar 02 2008
  

       If the poster was simply confused about the makeup of types of jet engines, then it's a valid combo of technologies - but not original, and not an exceedingly good combo.   

       However, since that's not what's written, I don't see a problem with this getting an "[m-f-d] hair curlers for bowling balls".
lurch, Mar 02 2008
  

       I think we could assume that he has simply used the term "Ramjet" wrongly through ignorance, if we were feeling kindly disposed. It may not be original, but neither is it really baked. It may not be a very good idea either, but it was presumably good enough for NASA to invest tens of dollars (if not more) in, which suggests it's not a really awful idea.
MaxwellBuchanan, Mar 02 2008
  

       But it's an idea along the lines of saying, "NASA should build bigger rockets." It's got nothing about how to, and two big technical errors (and several writing and spelling errors). It's also about something fairly obvious--using magnets as frictionless supports--which we get about once a week here.   

       It's not necessarily bad, there's just nothing good in it. Magnetic bearings may not be magic to NASA, maybe, but they were to [SIVOLC]. I'm not marking for deletion, but this isn't a HB-worthy idea.
baconbrain, Mar 02 2008
  

       It's not really like saying "NASA should build bigger rockets" - it's more like saying "NASA apparently has or had a fairly large programme dedicated to this, so it's not really "magic magnets" nor "stream of consciousness".   

       I'm not saying it's a great idea, just that both possible MFD grounds seemed unreasonably harsh to me.
MaxwellBuchanan, Mar 02 2008
  

       No, sorry, you are the one who noticed NASA was working on it. [SIVOLC] didn't know that, didn't look for and had never heard of magnetic bearings. And it was magic to him.   

       Here's a sentence from the linked article. "A probe senses the position of the rotor, and a feedback controller keeps it centered in the cavity." There's nothing like that concept in the idea or in the toy referred to.   

       I'm not MFDing for anything, I seldom do. I just think it's a poor idea. Good discussion, though. Thanks.
baconbrain, Mar 02 2008
  

       //And it was magic to him.// Well, I think it was naive of him, to extrapolate from a toy magnetic bearing to a real one, but I don't see that that makes it magic to him.   

       The early annos were pretty unanimous (after pointing out that he didn't mean 'ramject') that magnetic bearings for serious heavy applications were silly or impossible. They may be impossible, but they're clearly neither silly nor magic.   

       Anyway, it looks as if we scared him off back in '04, so us old gits can go back to discussing custard in peace.
MaxwellBuchanan, Mar 02 2008
  

       I still think this is pointless attempt to hybridize two concepts that are not compatable. Magnetic bearings make sense when the forces are easily contained and where weight is not a factor. In a jet engine weight is a huge factor as are the forces involved. Unless these are hyper powerfull super lightweight bearings then the idea simply does not fly. I will post a link with a cutaway of a jet engine and let people judge for themselves. Remeber for jet bearings to float free they must repulse the entire force produced by the engine and any side loads to sub-millimeter clearance. The compressor cannot move inside the housing due to close tollerences and the fact that rotating out of plane would fataly destabilize the assembly.
WcW, Mar 03 2008
  

       The idea as stated does not make sense in a conventional jet either, as the compressor wheel would simply fly out of the front of the engine if you don't hold it in.   

       In a jet engine the gravitational weight of the components becomes insignificant once the engine is spinning. I would imagine that the airflow is calibrated so that the axle would still stay in almost exactly the same place if you removed the bearings.   

       However, the major force in play in a jet is thrust, which only ever pushes the rotor forwards, so applying a repusive electromagnetic force to the bearing as the thrust increases would reduce the sideways load on the bearing. It could even be done mechanically using induction from the rotor.   

       Any magnetic force that you add to a traditional bearing to discourage the axle from leaving centre will reduce the load on the bearing. If the rotor weighs a tonne, repelling it vertically with a tonne of force will help, albeit minimally once it's up to speed.
marklar, Mar 03 2008
  
      
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