Using UFLOW to model Reynst-ish engines

[pezman]

Here's an idea to model engines with a single intake. Build a symmetrical model -- basically two copies of the engine with the bottoms "stuck together" in the middle. The set identical initial conditions on each side of the virtual bottom. The interface between the two sections shoudl act just like a solid wall.

A similar idea can be used to model Valved PJs, but you get into trouble once the pressure at the boundary goes negative (i.e. how to simulate the valves opening and relieving the vacuum).

I figure that building jam-jar models might be helpful since everyone talks about how counter-intuitive they are -- the ones that look good often suck and the fugly ones sometimes wail.

[RG Rhodes]

Hello Pezman-

I'm currently hustling around putting together an FWE with Reynst
intake as you have probably read- maybe too many posts about it-
but in my sketchbook is the proposed follow-on design which consists
of two FWE chambers, the stacks joined in a Y to keep things in time,
and no partion or wall between the chambers. I wonder what UFLOW
would think of this arrangement ? C.C.'s joined base-to-base.
Do you run UFLOW?


Didn't someone build something like this? Graham Williams?
Can't find it.


RG

[pezman]

Sounds like Bruno's BCVP.

I did a simulation of the BCVP -- basically running one cycle then taking the state of the engine at the end of that cycle and using the calculated density as a compression figure.

The conclusion that I came to was that the BCVP as drawn would build up too much pressure, stop breathing and then stop running -- kind of like a jam-jar that got too hot.

At any rate, I think that you could use UFLOW to study whether the fluid separating the two CC's would do the trick. Just set the initial conditions (I usually heat the air in the CC up to 3000 degrees) and see if the engine cycles as you expect. I usually run until I get a pressure peak in the CC and then plug that back in as an initial condition for the next pulse. I think that the big thing to look for is how much mass flow you get on the intake cycle.

If you post a drawing, I could take a stab at a model. I also posted the BCVP model a while back. You might be able to find it -- or I could repost it (provided I can remember where it is). I did a model of a Lockwood and it really did a god job of demonstrating that the jet would run. I also have a model of Mike Everman's pipe-wood around here somewhere (that one runs too). Always nice when the model fits the reality.

[Mike Everman]

Hey, Pez, I'd like to see that pipewood model. Never made one myself. I have however had good luck with closed end models for jam jar, that is mostly closed, down to a hole of 1mm at one end. A little leaky, but the highpoints are all there.

[larry cottrill]

I have however had good luck with closed end models for jam jar, that is mostly closed, down to a hole of 1mm at one end. A little leaky, but the highpoints are all there.

Mike -

In my UFLOW models of FWE and the like, that's what I refer to as the 'spark plug leakage'; why did you think I always put the plug mount at the very end? ;-)

L Cottrill

[RG Rhodes]

Pezman-

Well, I'm making dwgs now, probably have them ready to post by
middle of next week. But- can't post from this comp.
I can use one at Mama's office the following weekend. Maybe I can
find a way to put them up sooner, but that's the situation at pres.

Of course this is no blast-compression set-up, just two Reynsts
hooked together. Probably no more thrust than the sum of thrusts
of two seperate ones. The idea is to avoid an engine quitting on one side of the vehicle, generating yaw. With this set-up, it's either go or
no-go.

I'm really curious to see what the program will make of this. Thank
you very much for your generous offer, and I'll get this up ASAP.

RG

[RG Rhodes]

Hello Pezman-

Going to try our first attachment. This is a sketch of the butt-to-butt
Reynst. Do you think UFLOW can see into this thing? I'm very
curious.

Whatcha think?

RG

[jmhdx]

My instincts tell me the seperation of the two chambers would be unecessary. Otherwise that should work. I sketched up a barrel shaped chamber and immediately wondered if it could spin and that led me down a whole new path.
Once running as drawn ever increasing a small hole between the two chambers might shed light on the reactions.
Regards,
Mike.

[RG Rhodes]

jmhdx-

Yeah, I was kinda thinking about something like that myself. Mark posted
a website on Eric,s thread about supersonic shock waves emitted by
one of his engines. This site belongs to a researcher exploring toroidal
vortices, and he displays some amazing video. Have you seen it?

He has found a way to model these things in slow motion by using some
kind of fluid, maybe water (?) and the one that struck me was the two
"smoke rings" colliding face-to-face. They seem to blend for a short time
and the suddenly sort of explode into a disk. I was suprised at the
energy levels seemingly existing in this transformation. One of the most
beautiful natural phenominon I've ever seen.

Inside the c.c., the disk cannot form and all that energy will be
manifested in some other way. What way? Who knows?
I wish I knew how this fellow is modeling his vortices. It would be
fun to make a clear plastic c.c., equipped with something like a
camera iris in the middle, and watch what happens.

I,m not sure I'm following you about the rotating chamber. It is
rotating about the longitudinal axis of symetry?

RG

[Bruno Ogorelec]

I did a simulation of the BCVP -- basically running one cycle then taking the state of the engine at the end of that cycle and using the calculated density as a compression figure.

The conclusion that I came to was that the BCVP as drawn would build up too much pressure, stop breathing and then stop running -- kind of like a jam-jar that got too hot.

Yes. Many people have arrived at that conclusion. No one seems to have made the next step.

[Bruno Ogorelec]

Seriously, I'd guess you have some sort of E shaped design that bleeds some of each pulse, to keep it from overdriving?

Ben, do you remember where I got the confirmation for the idea of opposed combustion zones in the same tube? Esnault-Pelterie. Before that, I only had a vague idea of somehow one combustor firing into another to compress it. With Esnault-Pelterie, it snapped together. Do you have a sketch of the Esnault-Pelterie engine somewhere at hand? See where its exhaust is located.

[jmhdx]

jmhdx-

Yeah, I was kinda thinking about something like that myself. Mark posted
a website on Eric,s thread about supersonic shock waves emitted by
one of his engines. This site belongs to a researcher exploring toroidal
vortices, and he displays some amazing video. Have you seen it?

He has found a way to model these things in slow motion by using some
kind of fluid, maybe water (?) and the one that struck me was the two
"smoke rings" colliding face-to-face. They seem to blend for a short time
and the suddenly sort of explode into a disk. I was suprised at the
energy levels seemingly existing in this transformation. One of the most
beautiful natural phenominon I've ever seen.

Inside the c.c., the disk cannot form and all that energy will be
manifested in some other way. What way? Who knows?
I wish I knew how this fellow is modeling his vortices. It would be
fun to make a clear plastic c.c., equipped with something like a
camera iris in the middle, and watch what happens.

I,m not sure I'm following you about the rotating chamber. It is
rotating about the longitudinal axis of symetry?

RG

If the chamber rotated as the exhaust gas exited through vanes connected to the chamber as a whole, work with me here, would the rotation assist or resist the incoming air/fuel?
Any ideas?
Mike.

[RG Rhodes]

Mike-

Well, I thought about this into the wee hours and came to the conclusion
that you are onto something.

Suppose we have a Reynst pot with a hole in the c.c. head, where one
would mount a spark plug on centerline. We then mount this c.c. on
bearings so that it can spin freely. We have equipped the intake/exhaust
port with the blades you mentioned at an angle such that rotation of the
c.c. is caused by gasses blowing out the port. If we now introduce
compressed air into the spark plug hole (plug missing) we can cause the
c.c. to rotate. If we then turn off the air, and let the c.c. continue to spin
of it's own momentum, we would find that the blades will tend to pull
more air into the plug hole and out the port. In order to force air into
the c.c. from the port, the angle of the blades would have to be reversed,
and this would need to happen with every cycle. But-

Suppose we had -two- sets of blades. We have a nicely rectified intake
on the Reynst, and so we could arrange one set of blades to see only
exhaust, and the other seeing only intake air. If these were connected
mechanically, energy taken from the exhaust could then be transferred to
the intake air. Following this one step further, could we mount a
turbo-charger to the exhaust stack, forcing air into the intake?

If so, then have you invented a turbocharged Reynst valveless pulsejet?
Perhaps so.

RG

P.S. One of the resident wizards has probably thought of something
like this and it would be interesting to hear from them. I can't think of
any thermodynamic reason this idea should be regarded as not possible.

[jmhdx]

Thanks for your comments RG, I don't want to re-invent the turbo jet and I think moving parts are best avoided but I do try to mentally explore every possible avenue. I dont think it would be practical to exchange expansion energy for compression as in a turbo jet but the rotating vanes might provide some rectification in either direction. If the exhaust vanes delayed recompression from the rear then a smaller/longer intake could be used which in turn would force more expanding gases through the exhaust. Having said that, shorter cycle periods would seem an ideal.
So many things to think about.
I am still not disuaded that an almost hollow tube could have constant flow through with only the correct geometry to allow the many tricks of fluid dynamics to accelerate the air.
Mike.