New engine -- SP 14

[Bruno Ogorelec]

George,

Thank you for the suggestion, but the inlet _is_ located where the flow is the slowest. The initial entry passage of air into the engine is in fact a diffuser, but its slope on my diagram is so gentle that it is difficult to see. This is certainly something I will consider carefully.

[George]

OK, i see it.

I was thinking that all the folded PJ can be moved in a circular form!

it's an interresting way to explore... good food for my brain !

[Bruno Ogorelec]

I was thinking that all the folded PJ can be moved in a circular form!

George, not only the folded ones, but any other, too.

[George]

I think i understand, the others pj are circular but you can have a fresh air flow in the middle of the cc, is that you're saying ?

Like these "anti" Tharratt ?

(i'm coming back tomorrow)

[Bruno Ogorelec]

I think i understand, the others pj are circular but you can have a fresh air flow in the middle of the cc, is that you're saying ?
Like these "anti" Tharratt ?

Yes, more or less. The longitudinal section of any pulsejet can be rotated around some outside axis to create its annular version. Then you tidy up the details, adjust the dimensions etc.

The engine is nor really a Tharratt. I mistakenly called it so in teh first version of my review of valveless pulsejets. The latest version (the fourth so far -- but only the first has been published!) should come out soon and correct the error. This is actually something that I have 'invented' by misunderstanding a description of the Tharratt engine. Tharratt actually designed something much more sophisticated. But, my 'quasi-Tharratt' is a valid design. It works. I know a guy who built one from old electrical conduit tube. It was rather long but it worked.

[Viv]

How about an anular Schubert:-) its from an interesting water heater patent i found quite a while ago.

Viv

[George]

Hi,

I had a great fun to imagine in annular design the reynst pot..

BUT, it's seems to complicate the construction, the scaling would be hard to realise and you have certainly most drag effects than the "normal" type due to the increase of the internal surfaces.

So, wich interrest unless you wants to make a ramjet inside ?

[Bruno Ogorelec]

So, wich interrest unless you wants to make a ramjet inside ?

Well, just take a look at your sketch. It looks like an engine almost ready to mount on something or inside something. The 'normal' Reynst looks like it needs a number of things before it is ready to be used for anything but making noise. It all depends on the application you have in mind.

[George]

Yes it's look's like an engine ready to mount but it's looks only.

I don't forget that streamlined shapes or augmentators works only on a really running engine, the difficult is to built the engine...

I've already design the air inlets for my Reynst project and a carbon body to enclose the engine but i have to build the engine first!

I think it's the same for your BCVPJ, if it the cc runs on an simple unfolded tube, you won ! You don't have to realise the entire engine first.

[Mike Everman]

You guys are having too much fun.

While I like 14 a lot, the intake and exhaust on the same side, while elegant, is not a slam dunk for certain, right? I can't wait to try this idea at some point, but I have reservations that the annular (very wide skinny engine rolled in a hoop) is going to burn uniformly. If some quadrant flame front advances faster than another, it sounds like a recipe for flame out or just plain instability. Even if you segment it around the perifery, then you probably have synchronization issues.
All that being said, if it turns out better off in-line, and without enclosed areas that would be hot spots without cooling, it could look like this:

[George]

Interesting way Mike, the enclosement of the cc would be an elegant solution to put 3 or 4 pj in one annular engine !

In these case, why do choose a design with outer shrouds, i think that internal flow would be more efficient and probably reduce vibrations.

[Mike Everman]

In and out is for cooling, and an attempt to use Bruno's idea for thermal ramjet style air heating.

[resosys]

I've been pondering Bruno's SP14 for a few days now. It's so damn elegant.

I have some fears about misfiring and odd pressure imbalances as mentioned by Mike.

I threw together a sketch of an idea I had. (getting in practice with Solidworks, really!)

It almost seems as though the proportions are way off. The outside ring, where the business of the engine sits, might be squished down into a very shallow ring.

I haven't worked out the tailcone portion yet. There has to be some magic to mixing the exhaust with the center flow and intake push to get a big gain in thrust.

Adding a carb or second intake inlet to the combustion "ring" may help. Maybe NACA ducts that flow into the chamber but are still small enough that the combustion cycle doesn't see them as a hole, like the tear in the triangle engine.

The intake outflow should aid in pulling air around the front radius. I've seen this type of setup on air augmentors in large truck intake systems that were fed by a compressor.

My brain hurts from all the database work I've been doing. Hopefully some of the above and image make a little bit of sense.

It's beer thirty around here.

Chris

[cudabean]

Chris,

That's nice. I like how you have streamlined it. My only suggestion would be to rearrange the exhaust so that it "hugs" the interior thereby heating the interior air passing through as much as possible, which should also help cool the exhaust and hopefully quiet it down a little.

Here's a slightly new idea I just thought of. The old Boeing 707 had a flower petal shaped flange for an exhaust that helped to mix the hot exhaust with the ambient air. It's main purpose was to suppress the noise. I wonder if a similar idea could be beneficial in the SP 14 + derrivatives, in an attempt to get the two gas pathways close to the same temperature. I think it could be beneficial if it cooled the exhaust, thereby decreasing volume and removing velocity and at the same time heated the interior air thereby increasing its volume and velocity.

cudabean

[Mike Everman]

what has Bruno done to us? It is a very compelling idea, isn't it? Nice work on Sworks, Chris! Fat CC, check it out! I have a spreadsheet that converts Lockwood and Kentfield to annular dimensions. Let's build an engine, Chris! I'll be testing the torch/vacuum forming this weekend. I can make the two half torii we need, and Fed-X them up to you. I'm leaving for Mexico next Wed, so I'll work on some dimensions for your configuration tonight.