Jam Jar Turbine

Post by **Mike Everman** » Sat Nov 22, 2003 4:21 pm

Something for Bruno's over-rated originality file!
I don't know whether this will work or not, or if it's missing something; whether it's been thought of or would any efficiency whatsoever.
I suspect a certain pipe length would dictate only one working rpm, so you may have to have a variable pitch prop attached to it and govern it closely.
What fun, though? It'll be interesting and simple to try!
Thinking the pipe length will be shorter because it's harder for the exhaust to fight its way out of the centrifugal force.

Bruno Ogorelec · Post by **Bruno Ogorelec** » Sat Nov 22, 2003 8:02 pm

I like the simplicity, but the efficiency would probably be terrible.

Stephen H · Post by **Stephen H** » Sun Nov 23, 2003 10:49 am

that looks interesting..and yea originial allright!

Stephen

Bruce · Post by **Bruce** » Sun Nov 23, 2003 10:52 am

As a pure reaction turbine its efficiency would be quite low. It's much better to use a combined reaction/impulse turbine when you're trying to extract the maximum amount of energy out of a gasflow.

But then again -- you're talking simplicity not efficiency right :-)

Post by **Mike Everman** » Sun Nov 23, 2003 11:21 am

It's a "to heck with efficiency" may be a nice demo, maybe a spinning top for fun.

cudabean · Post by **cudabean** » Sun Nov 23, 2003 5:27 pm

I think I understand it, but maybe not. Is the combustion taking place in the ring? But it's pulsating combustion, right?

If thought of a way in which this could be modified into a simple turbojet:

devise an intake near the hub. Place radial diffusers to help accellerate the intake air towards the outer ring combustion chamber and you'll have centrifugal compression. Centrifugal force could also then be borrowed for fuel pressurization.

cudabean

Post by **Mike Everman** » Sun Nov 23, 2003 7:00 pm

I've got little jamjar theory under my belt, but I am proposing that centrifugal pressure increase is the goal. I like the pool of boiling fuel concept. Makes delivery a non-issue. the model is cut away depicting it in spun up mode, so fuel is perfectly destributed about the rim.

cudabean · Post by **cudabean** » Sun Nov 23, 2003 11:32 pm

Ah, yes. That makes sense. The standard jam jar model is impractical for transportation applications because it relies on gravity to pool the fuel, but with the centrifugal action of your refinement in the design, it opens up new possibilities that could well include making things move. Fuel delivery and pool replentishment isn't a total non-issue in that you cant just let it fly out straight into the pool because it would proabaly ignite before it had a chance to pool but I suppose a tube running from the hub straight out to the rim with an exit right below the normal pooled fuel level would suffice.

So what other details are part of the design? Why have three or four exit tubes along the inner rim? Why not have ten to twenty smaller tubes along the upper side of the rim bending so that they exhaust straight back? But I guess what you have there now kind of reminds me of a Harrier's vectored exhaust.

The remaining exhaust that doesn't go into generating rotation could be used for thrust.

I wonder about vibration due to pulsation. Would rotation dampen it significantly?

cudabean

Post by **Mike Everman** » Sun Nov 23, 2003 11:51 pm

So what other details are part of the design? Why have three or four exit tubes along the inner rim? Why not have ten to twenty smaller tubes along the upper side of the rim bending so that they exhaust straight back? But I guess what you have there now kind of reminds me of a Harrier's vectored exhaust.

The remaining exhaust that doesn't go into generating rotation could be used for thrust.

I wonder about vibration due to pulsation. Would rotation dampen it significantly?

cudabean

I bent the tubes such so that the slipstream won't impair intake; as you see I didn't try very hard. Still a work in progress, but I'm starting to think that you could allow air in more toward the hub, and the exhaust farther out and more tangentially. Centripetal accelerations bring an interesting twist I wish we had on the engines we're talking about. Imagine if our VPJ's had a strong apparent axial acceleration to bias things! Everything would be different.
Viv educated me a bit on jam jar theory off-line, so I'll post a new version knowing what I know now.
As to thrust, I think all the work should be dumped into creating torque.
But I'm sure all of this has been thought of before!!! ;-D

Viv · Post by **Viv** » Mon Nov 24, 2003 12:17 am

Mike Everman wrote:

So what other details are part of the design? Why have three or four exit tubes along the inner rim? Why not have ten to twenty smaller tubes along the upper side of the rim bending so that they exhaust straight back? But I guess what you have there now kind of reminds me of a Harrier's vectored exhaust.

The remaining exhaust that doesn't go into generating rotation could be used for thrust.

I wonder about vibration due to pulsation. Would rotation dampen it significantly?

cudabean
I bent the tubes such so that the slipstream won't impair intake; as you see I didn't try very hard. Still a work in progress, but I'm starting to think that you could allow air in more toward the hub, and the exhaust farther out and more tangentially. Centripetal accelerations bring an interesting twist I wish we had on the engines we're talking about. Imagine if our VPJ's had a strong apparent axial acceleration to bias things! Everything would be different.
Viv educated me a bit on jam jar theory off-line, so I'll post a new version knowing what I know now.
As to thrust, I think all the work should be dumped into creating torque.
But I'm sure all of this has been thought of before!!! ;-D

No it has not that I have seen, some one correct me if they have a ref.

Does it need a lot of pipes? or would a few grills work?

Four grills would be neet I think, Mike look at the venturie in that picture I sent you in Nicks version it made a huge differance to the power of the jam jar and it was pretty good to begine with.

They do not rely on fuel pooled in the bottom to work, it normally happens that way simply becouse it is poured in and then lit.

In Reynsts engines it is fed in at the top of the pot from an anular slit, again in Nicks version it worked when fuel was dropped on top of the jar with a pipet or droped in to the jar.

Attached is a scan from Reynsts Pulsating combustion.

Top is the standard jam jar

Middle is a steel version (this is the one Nick built)

Bottom is the highly developed reynst combustor

These are thermal engines primarily not resonant engines as per the normal pulse jet, the Reynst combustor is the bastard child of both:-)

Viv

Post by **Mike Everman** » Mon Nov 24, 2003 12:44 am

The whirls are going to get smashed flat by centripetal force, so maybe in this case they should be encouraged to form parallel to the plane of the fuel surface... Isn't the "eye" of these whirls the highest compression state, being the lowest velocity?
And in the second diagram, what happens in the exhaust phase? Do the whirls keep going in the same direction?

I like the grills idea.

Bruno Ogorelec · Post by **Bruno Ogorelec** » Mon Nov 24, 2003 1:11 pm

Maybe one should do a toroidal tube, like a bike inner tube.

On the outer circumference, punch a series of holes so that their inner edges project slightly inwards. Also, they should not be completely radial, but angled, so that the puffs from them give a rotating direction to the wheel.

On the nner circumference, punch a similar series of holes but angled at the opposite direction.

Pour some alcohol into the tube and ignite at one of the holes. Give it a push to rotate in the direction the outer puffs would be pushing it.

Outer puffs will work on a longer lever arm and overpower the inner ones (which will push in the opposite direction). You will also help it by giving it the initial twirl.

Gradually, as the speed and the centrifugal force increase, the flow will fall into a one-way pattern -- into the tube from the inner holes and out of the tube through the outer holes. The inner ridges around the holes will prevent the fuel from spraying out. This shoudl eventually be spinning quite madly.

[/u]

Post by **Mike Everman** » Mon Nov 24, 2003 1:24 pm

me wrote:but I'm starting to think that you could allow air in more toward the hub, and the exhaust farther out and more tangentially. Centripetal accelerations bring an interesting twist I wish we had on the engines we're talking about. Imagine if our VPJ's had a strong apparent axial acceleration to bias things! Everything would be different.

great minds in the same gutters again. I like the idea of the exhaust tubes in the extreme outer perimeter, reaching thru the fluid to the toroidal chamber, if I understand you correctly. That's slick, and may have to make it out of glass, so you can see how cool it is inside.

Oh, yeah, Where in the Whorl is the flame front? ;-D

Bruno Ogorelec · Post by **Bruno Ogorelec** » Mon Nov 24, 2003 1:43 pm

Mike Everman wrote:Oh, yeah, Where in the Whorl is the flame front?

Um... a tough question. Theoretically, in a combustion process taking place in a toroidal vortex, the flame front is a sheet wound spirally around itself throughout the vortex, like a danish pastry donut. The place of the higher pressure is not the 'eye' of the donut but the center, innermost ring of the vortex, towards which everything is rotating. That keads the vortex to self-compress. That is what makes the toroidal vortices so durable. You can shoot a proper smoke ring over a considerable distance before it goes apart. Of course, a burning vortex will explode much sooner, as its self-compression is counteracted by the fast-rising inner pressure.

Mark · Post by **Mark** » Mon Nov 24, 2003 3:24 pm

brunoogorelec wrote:
Mike Everman wrote:Oh, yeah, Where in the Whorl is the flame front?
Um... a tough question. Theoretically, in a combustion process taking place in a toroidal vortex, the flame front is a sheet wound spirally around itself throughout the vortex, like a danish pastry donut. The place of the higher pressure is not the 'eye' of the donut but the center, innermost ring of the vortex, towards which everything is rotating. That keads the vortex to self-compress. That is what makes the toroidal vortices so durable. You can shoot a proper smoke ring over a considerable distance before it goes apart. Of course, a burning vortex will explode much sooner, as its self-compression is counteracted by the fast-rising inner pressure.

Bruno,
I'm just glad to see that there's something in Reynst's book that actually runs, the jam jar. All those other funny pretzel engines must have been put in there to fool us. What's worse, my copy of Pulsating Combustion is in French, German, and English with English translations after the foreign language chapters. Trickery in three languages!
Mark