A New Type of Hot Air Engine

[Tom Booth]

Fascinating read.
Do we know what happened with normandajc's proposed engine?

He never contacted me directly with any CAD drawings or anything. His last post on that thread is the last I've heard of anything. Unless someone else has any information, I guess not. Could be that big engine from China for all I know.

[Tom Booth]

....

My thoughts turn to pumping cold atmosphere into the right direction of a superheated all metal tesla valve. The air will be heated and expanded, but forced to move out of the valve through what looks to me as a constant volume compression cycle(reference youtube videos of the tesla valve flow characteristics). The air can then be used to power a turbine. And the vacuum generated once its going may eliminate the need for the cold air pump at the start......hmmmm....

This is a rather remarkable idea, I did not really understand the first couple of readings through.

A Tesla valve as a kind of jet engine driving a turbine!

All you need to do is heat up the "valvular conduit" and the expanding gas inside is forced to exit one way, leaving a vacuum behind that draws in more air to be heated.

The toroidal version would certainly lend itself to such a heat engine of what may be the ultimate in simplicity.

It took a third or fourth reading to understand what you were saying. I had a picture in my heat of this superheated valve somehow being used to drive a piston in a cylinder.

Might just work as a water pump as well. A simplified version of this idea but with no moving parts:

viewtopic.php?f=1&t=5413

https://youtube.com/shorts/xaoJMKB0QRs?feature=share

[VincentG]

Thank you, it seems a bit farfetched, but I can't really see it not working to some extent at least. Easy enough to test. I'll have to get the file that NightHawkinLight used in his youtube video and cnc one out of some aluminum bar flat stock I have. It seems to be the most well designed version I've seen.

[Tom Booth]

Thank you, it seems a bit farfetched, but I can't really see it not working to some extent at least. Easy enough to test. I'll have to get the file that NightHawkinLight used in his youtube video and cnc one out of some aluminum bar flat stock I have. It seems to be the most well designed version I've seen.

Getting carried away with this idea now I guess, but I was thinking about combining the theoretical drag reduction of the "shark skin"" toroidal Tesla fluid diode with the converging and diverging nozzles in things like turbines, injectors, ejectors, garden hose nozzles, pressure washers, water jet nozels etc.

Basically the series of toroidal vortices either dilating or becoming smaller and smaller, for converting high pressure to a high velocity stream, venturi effect vacuum, entrainment etc.

[VincentG]

I don't think that's out of relm of possibility. I'm sure the basic tesla valve has alot of room for improvement. You could also reduce the size of the valve itself, progressively tapering it towards the exit and then open it back up and encourage laminar flow, similar to a rocket engine.

The thing I struggle with most is a practical way to harness turbine levels of rpm in the diy setting.

It might lend itself better to powering a large crank based diaphram type engine.

I do think it has the potential to have an incredibly high DTU...my made up acronym of delta temperature utilization. Or in other words getting the most pressure possible from the hot air. And the added benefit of continuous flow.

With 3d machining of a clam shell design, its possible to make a full round profile tesla valve. Whether or not its worth the added effort I don't know. The 2d valve appears to function well enough.

[Bumpkin]

Something I ran across that might relate or be thought-fodder for the topic a few pages back: https://go.gale.com/ps/i.do?id=GALE%7CA ... hType=true

Bumpkin

[VincentG]

Bumpkin,

Thanks for the link, I will try to join tomorrow so I can view the information.

[Tom Booth]

Bumpkin,

Thanks for the link, I will try to join tomorrow so I can view the information.

I couldn't find any means of joining, but clicked on the text: "Search for another location" and it took me directly to a paper: NOVEL HOT AIR ENGINE AND ITS MATHEMATICAL MODEL--EXPERIMENTAL MEASUREMENTS AND NUMERICAL ANALYSIS.

Didn't work a second time though. I found it on several other sites also. It can be downloaded as a PDF here:

https://akjournals.com/view/journals/60 ... le-p47.xml

[VincentG]

Thank you Tom. I do wish they would have recorded the observed operating pressure achieved with the test engine. 2 watts of estimated shaft power is pretty impressive considering the displacement.

[Tom Booth]

I don't think that's out of relm of possibility. I'm sure the basic tesla valve has alot of room for improvement. You could also reduce the size of the valve itself, progressively tapering it towards the exit and then open it back up and encourage laminar flow, similar to a rocket engine.

...

I found my toroidal Tesla valve sketch reproduced on another forum here from way back in 2013:

http://brassgoggles.co.uk/forum/index.php?topic=41939.0

That was about a year after I had posted it on my Facebook timeline April 2012

https://m.facebook.com/photo.php?fbid=1 ... 1072200061

A post on that forum linked to a patent for what appears to be such a tapering fluid diode intended for use as a muffler to reduce back pressure, firearm silencer etc.

Curious that this patent was applied for just a few months after the post on my Facebook timeline, I wonder.

Resize_20230402_115512_2091.jpg (33.13 KiB) Viewed 1672 times

https://patents.google.com/patent/US20120273297

What I was actually looking for was a 3D print file I thought I had found maybe a year or two ago of the toroidal type Tesla valve. Can't seem to locate it now though.

[Tom Booth]

Thank you, it seems a bit farfetched, but I can't really see it not working to some extent at least. Easy enough to test. I'll have to get the file that NightHawkinLight used in his youtube video and cnc one out of some aluminum bar flat stock I have. It seems to be the most well designed version I've seen.

Have you been able to do any machining or testing on this yet?

I'm wondering about the thermal properties of aluminium being highly conductive vs. maybe 3D printed plastic or ceramic.

I have a notion that in the toroidal version, heat retention would likely be helpful of even necessary in order to sustain a toroidal vortex for an extended length of time.

I bought a second hand 3D printer a year ago, if not two years ago now, but got hung up when the 3D rendering software wouldn't run properly on my old clunky laptop.

I went out and purchased a brand new computer just to use with the 3D printer, but then got sidetracked with other projects and responsibilities, so haven't even gotten around to installing the software on the new computer yet, never mind actually learning how to use it.

There just never seems to be enough time.

[Tom Booth]

This post, about using the Tesla diode as a "passive supercharger" is interesting. And as a propulsion device generally.

http://brassgoggles.co.uk/forum/index.p ... #msg884241

The entire thread is quite interesting actually. The part about the internal structure of some flutes having a similar "stepped" construction etc. "Tuning" in a 2 cycle engine etc.

[VincentG]

Tom, unfortunately as the weather gets nicer my attention is drawn to working on the property. I am still working on the next phase and subsequent post for the LTD engine development.

I have been mulling over the tesla valve idea and wanted to start designing something easier to 3d print for testing. Your design looks like a great starting point. If you don't mind, can I use that for some testing for my planned use, which is as follows.

I was thinking of exactly using the valve for passive supercharging of an ICE. I thought if we can use engine heat to heat the valve on the intake side of the engine, maybe we can get some positive pressure out of the thing with no parasitic drag like with a turbo or supercharger.

My next thought was to combine elements of the Brayton cycle into the exhaust of the ICE using a tesla valve. Picture cooling the hot exhaust gas in a heat exchanger, then it flows into a tesla valve, where the valve is externally reheated with redirected upstream(uncooled) exhaust gas. After that it goes into an expansion zone similar to a rocket engine, where the pressure should in theory be reduced below atmospheric.

Even if you could get +1psi on the intake, and -1psi on the exhaust, that would be a significant gain, with no significant losses.

For what it's worth, I have been bouncing my ideas off of chat gpt. For better or worse, it is an incredible engineering resource that we now have at our disposal. It, with some careful directing, thinks that these ideas are possible, and also claims that there have been tests conducted for similar use cases, though it is unable to provide links, or many of the provided links are no longer found, interestingly. There is also mention of the valve being directly applied to the SE's regenerator gas path to reduce back flow.

Clearly the idea of using the valve as a heat powered compressor is not new. And no wonder. Using the PVT graph of air, if compressing air generates heat, and heating air generates pressure, if the valve itself is or can be modified to be effective, it will produce a continuous flow of compressed air.

[Tom Booth]

....
I have been mulling over the tesla valve idea and wanted to start designing something easier to 3d print for testing. Your design looks like a great starting point. If you don't mind, can I use that for some testing for my planned use, which is as follows.

....

I'd love it!

I was anxious to get it 3D printed or something back when it first popped into my head and that's the main reason I bought a 3D printer, not that I won't have other uses for it.

IMO the toroidal vortices it might theoretically create would be self reinforcing, unlike Tesla's earlier flat 2D design that pretty much instantly destroys itself with back turbulence.

https://youtu.be/72NdY9sZ8Wk


A bit of vortex ring science:


https://youtu.be/0odYvE4k9Eg

[Tom Booth]

Of course, the vortex could be sustained longer by reducing frictional loses by making it a toroidal vortex FRACTAL:

Resize_20230403_133701_1522.jpg (198.02 KiB) Viewed 1631 times

That is, of course a 2D slice of 3D wave-like ringlets.