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Pulse Jet Generator

A miniature pulse jet running a generator
  (+4, -2)
(+4, -2)
  [vote for,

A pulse jet in one of the more simple forms of a jet engine and uses PDE. Using a miniaturised pulse jet (only between 100mm and 200mm long) connected to a generator power could be generated. The power from the explosion producing the exhaust velocity would power a turbine connected to the mini generator. This would allow a variety of fuels to be used in the generation of electricity (alcohol diesel petrol etc), and the potential for combustion of Hydrogen.

This idea is similar to the Jet Engine + Generator setup in the new Jaguar so there is a real basis to the idea. This differs in that the system would be tiny (small enough to use on a bicycle).

Problems associated with this is the idea of the slowing down of the air flow within the pulse jet due to the smaller size. The air "sticks" to the side of the tube and as the tube gets smaller the amount of air flowing through unaffected with this "stickiness" reduces, posing the problem that the pulse jet could potentially be choked off.

The second problem is that a pulse jet of this size would have VERY low thrust so that generator would need to be low geared for it to spin, and hope that the exhaust velocity is great enough to produce viable generator spin speeds.

Apart from these two problems I cannot see anymore possible problems in the feasibility of this "halfbaked" idea.

qwertyuiop23, Jan 20 2011

Mini Pulse Jet http://www.youtube....watch?v=zn4YVYdp8lE
A video of a very small pulse jet working [qwertyuiop23, Jan 21 2011]

An Outburst Of Emulsion An_20Outburst_20of_20Emulsion
Another terrible Bohemian Rhapsofy parody ... [8th of 7, Jan 23 2011]


       That should explode rather quickly.
FlyingToaster, Jan 21 2011

       Note: Added a link of a small pulse jet not exploding
qwertyuiop23, Jan 21 2011

       I meant when it hit the fan.   

       ... though I'll grant automotive turbochargers seem to do okay despite pulsed pressure.
FlyingToaster, Jan 21 2011

       And that a pulse jet would be used
qwertyuiop23, Jan 21 2011

       Dammit! I hoped for a mind buckling Vernon idea
Zimmy, Jan 22 2011

       //Apart from these two problems I cannot see anymore possible problem// Perhaps [FlyingToaster] overstates the case, but he does raise what seems a legitimate third problem: the stress on the turbine blades (there is a turbine, yes?) and other components would have big spikes in it -- peak values would be higher than in an ordinary generator, and there would be many, many cycles of strain-relief-strain. Would pose a strength-of-materials problem, no?   

       I suppose the fact that this device has very low thrust is a partial answer to this. But why is low-thrust pulse-jet better than burning the same fuel in a continuous jet? It sounds like you have an answer to that question in mind, but could you explain it to us?
mouseposture, Jan 22 2011

       Pulse jets are quite noisy .... (the hint's in the name).   

       The Argus type pulsejet on the V1 had a similar problem of low specific impulse, hence the need for a catapult launch.
8th of 7, Jan 22 2011

       [8th_of_7]//Pulse jets are quite noisy// Perzactly. I was going to say: Any of the surviving British pensioners who remember the V1 will, on hearing this, immediately die of a heart attack. Actually, to be precise, any of them who hear the noise *stop* will instantly die of a heart attack.
mouseposture, Jan 22 2011

       So you suggest we start making them now so they are ready for 20 years time then?
Germanicus, Jan 22 2011

       I've always advocated using pulsejets as emergency engines on small aircraft: very light, very inexpensive.   

       Quickly going deaf while your tail is being set on fire could be the preferable option in many cases.
FlyingToaster, Jan 22 2011

       Actually, I was quite disappointed by the YouTube video. The engine is mounted on what looks like fairly thin, stiff wire. If it had any decent thrust, it would surely have bent this mounting. What's the efficiency of a pulse-jet in generating thrust?
MaxwellBuchanan, Jan 22 2011

       about 10% of a decent turbojet... could be increased to 25% by an augmenter and stuff.
FlyingToaster, Jan 22 2011


       Power density ... power density ... powerdensity ...   

8th of 7, Jan 22 2011

       <al dente> calamari calamari calamari </al dente>
FlyingToaster, Jan 23 2011

       // calamari calamari calamari //   

       ... let me go, Beelzebub has a platter keeping warm for me, for me, for me !   

8th of 7, Jan 23 2011

Just bunned a guy,
Put my cursor on the bread
Meant to fishbone him instead
MaxwellBuchanan, Jan 23 2011

       Once you add a turbine to a pulse jet, haven't you lost most of the advantages over a turbojet?   

       To put it another way, once you have approached the complexity and weight of a turbojet, why not have its higher efficiency and lower noise too?
spidermother, Jan 28 2011

       --Look up "Magnetohydronamics". This was a relevant fad a few decades ago...
Steamboat, Jan 30 2011


       " that should explode rather quickly "
normzone, Jan 30 2011


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