new concept of Stirling engine

[normandajc]

I was able to create a link that lasts longer
https://dracoon.team/public/download-sh ... pxamdP5twm
https://dracoon.team/public/download-sh ... sQvnTxHJyB

[normandajc]

Tom's proposal of the Tesla diode is interesting.
I tested it digitally with openfoam with a few trials.
If I find time, I will try to write a mathematical model. I would like to know if the design proposed by Tom is free of rights or if there are patents.

[normandajc]

Hello to all
on my site www.cyberquebec.ca/normandajc/ I made a small modification
I have added this film that presents the Stirling cycle
https://dracoon.team/public/download-sh ... VUDZ0Cialj
Regarding the Tesla diode, does anyone know if it is free to use? I found the Tesla diode an interesting product that deserves further development.

[Tom Booth]

Tesla's patents, I believe, have all expired. His patent for a "valvular conduit" seems very broad, so as to encompass the entire concept, it seems to me, though I'm no patent expert.

"The invention can be embodied in many constructions greatly varied in detail, but for the explanation of the underlying principle it may be broadly stated that the interior of the conduit is provided with enlargements, recesses, projections, baffles or buckets which, while offering virtually no resistance to the passage of the fluid in one direction, other than surface friction, constitute an almost impassable barrier to its flow in the opposite sense by reason of the more or less sudden expansions, contractions, deflections, reversals of direction, stops and starts and attendant rapidly succeeding transformations of the pressure and velocity energies."

The toroidal design may be sufficiently original, conceptually, for a "design patent", but I did not pursue that.

[Tom Booth]

Originally I had an idea that drag or surface friction could be reduced in cars, trucks, airplanes, etc. by giving them a wave-like surface in imitation of waves in nature: water waves on the ocean, the ripples in sand in the desert, fish scales and shark skin, etc. all have similar rippled forms

My reasoning being that, in general, everything follows the path of least resistance, so, logically, this wave shape is seen in nature because it offers less resistance to a fluid flow, than any other shape, even a smooth surface.

This Shark skin for example:

Screenshot_20201007-060517_crop_7_resize_85.jpg (15.91 KiB) Viewed 6242 times

Though it was Tesla's invention that prompted the idea of wrapping the shape into a circle to line the inside of a tube or pipe

It was an after the fact observation that this shape would likely generate a toroidal flow, or series of toroids.


Wind blown desert sand:

sand-ripples-delphimages-photo-creations_resize_87.jpg (26.07 KiB) Viewed 6240 times

And of course, waves on the water, blown by the wind:

identified-brent292_resize_68.jpg (11.79 KiB) Viewed 6239 times

[normandajc]

Effectively I think that a patent would have been possible on toroidal design.
If I write something about this process I will quote you.

[normandajc]

your animation is very realistic. I recognize it. Moreover, your animation is nice. My animation does not take into account the heat recovery during the cooling operation. I wanted to make an animation so that everyone can watch it and interpret it easily.

[normandajc]

In the forum "Animated Stirling Engine... 'gifs'"
I added an animated gif of the engine

[normandajc]

I wrote a preprint. It's not necessarily an easy read for everyone.
https://hal.archives-ouvertes.fr/hal-02977390v5
or
https://hal.archives-ouvertes.fr/hal-02 ... 5/document

[MikeB]

I'm not 100% sure I understand where you think that this "shark skin" would be beneficial - but if it is for the regenerator, then it seems to me that you will make things worse!

The basic design of a regenerator needs to be a compromise - you want to maximise surface area in order to maximise heat transfer, without impeding flow, however the whole point of "shark skin" is to minimise apparent surface area by control of boundary layers, i.e by having a thin layer of air/water that is in constant contact with the skin, but which is entirely stationary, and allowing outer layers of 'fluid' to pass by without touching the surface itself. It seems to me that this would massively REDUCE the heat transfer at the boundary.

[normandajc]

I agree. It takes a lot of surface area to get a good exchanger. What is interesting about the Tesla diode is that in one direction of fluid flow there is no pressure drop and on the contrary there is a pressure drop in the opposite direction. Tom Booth's version of the Tesla diode is an excellent idea.
Do not use the Tesla diode in the heat exchanger.

[Tom Booth]

I'm not 100% sure I understand where you think that this "shark skin" would be beneficial - but if it is for the regenerator, then it seems to me that you will make things worse!

My suggestion was intended for the interior of the tubes or "conduits" (Tesla's term) in normandajc's engine.

[Tom Booth]

I'm not 100% sure I understand where you think that this "shark skin" would be beneficial - but if it is for the regenerator, then it seems to me that you will make things worse!

My suggestion was intended for the interior of the tubes or "conduits" (Tesla's term) in normandajc's engine.

Earlier in the thread he stated: "At the end of the piston stroke a push rod can actuate a slide valve to direct the gas in one direction or another. This is very simple to do."

This use of push rods and valves would involve mechanical loses, inertia, friction, moving parts.

I thought that normandajc's engine design lended itself nicely as a potential application for Tesla's "valvular conduit", further reducing the number of moving parts.

Tesla had his ridges or "shark skin" offset in an alternating pattern. My contribution was the idea of making the ridges in a circular pattern on the inside walls of the pipes which would, theoretically form a series of toroidal vortices which would resist flow in one direction and enhance flow in the opposite direction.

Normandajc's computer modeling of the concept seems to support the idea.

I'm not at all sure what Sadi might have in mind.

[Tom Booth]

...the whole point of "shark skin" is to minimise apparent surface area by control of boundary layers, i.e by having a thin layer of air/water that is in constant contact with the skin, but which is entirely stationary,...

I'm not sure how relevant any of this may be, but I don't think it is true that the layer of air/water in contact with "the skin" is "entirely stationary". Quite the opposite.

The fluid trapped in a kind of swirling vortex would be in constant motion. It's friction reducing capacity would be similar to that of roller bearings or a roller transport type device.

conveyor-belt_resize_2.jpg (41.72 KiB) Viewed 5915 times

(Public domain image)

This does not eliminate, or necessarily even reduce local friction and/or potential heat exchange. It might even enhance heat exchange and create more friction as there is more surface area, and more fluid in contact with the skin. The arrangement, however makes the effective friction of the fluid flow directional.

There is great resistance to fluid flow in one direction but virtually no resistance to fluid flow in the opposite direction. However the fluid that is actually in direct contact with the skin is in constant swirling motion.

[normandajc]

What seems difficult to me, for a heat exchanger you need an extremely large exchange surface to have an efficient exchanger. But it is not necessary to create an exchanger with large internal volumes. I think it is possible to design the exchanger with cavities as proposed by Tom. I am in contact with a university institute of technology for a group of students working next school year on this engine. A specific study of the exchanger would be a possible subject.