large lamina flow build
Re: large lamina flow build
the inner tube is open on the hot end. The pointed end is just pointed for airflow purposes. the point is basically hollow. I wont be sharing the new design, I have too much time invested to just give it away.
Re: large lamina flow build
Thanks. I hope you are successful. Let us know when its on the market. It wouldnt be revealing any secrets if you share a video.
Re: large lamina flow build
By the way your video's say it's thermal lag, here you say it's lamina flow. ? ?
Re: large lamina flow build
It could also be called a Thermo Acoustic Pulse Engine, I don't think anone knows exactly what to call them. There was one supplied as a kit set called the "Whatisit" engine.
Ian S C
Ian S C
Re: large lamina flow build
It is "all of the above". I think the pulse jet principle best describes it. Inertia.
Re: large lamina flow build
I believe when you look at the design closely it follows the pulse engine (lamina flow) design rather than the thermal lag. Even though many people think they are the same thing there are significant differences both in design and function.
The thermal lag engine is typically designed with a shorter heating tube, contains no regenerator and is heated at the end of the heat tube (farthest from the piston). Its function depends on a the time delay for pressure to increase once temperature is changed as discovered by Tailor in the 60's.
The Pulse Tube or Lamina Flow engine has a longer tube, a regenerator, a pulse tube section and many times a constrictor. The regenerator is located at the farthest point from the piston and heat is applied at the interface of the regenerator and the pulse tube. At the opposite end of the pulse tube next to the piston is where the restrictor is located if needed. This engine functions due to the temperature differential across the pulse tube sets up a standing wave that produces the motive force.
The design discussed here at first doesn't look like either of these descriptions and is what contributes to the confusion. This disign contains a tube within a tube ultimately folding the pulse tube engine in half. Even thouh it looks like the tube is heated at the end like the thermal lag engine, it is actually being heated in the middle due to the folding. In earlier posts by the OP he references the use of a restrictor. Even though lated designs by the OP indicates both the restrictor and the regenerator material are no longer used, their function still exist. When tuned properly this engine can use the pointed part of the inner tube as a functioning restrictor. Many people have built a small test tube engine and made it function without regenerator material. This is because the empty tube can act as a regenerator and the same thing occurs in the OP's engine. The outer tube in this engine is the pulse tube and the inner tube is the regenerator. The length of the tubes are also a dead give away that this is not a TLE as Tailer describes and would cause far too much dead space for it operate as a TLE.
The thermal lag engine is typically designed with a shorter heating tube, contains no regenerator and is heated at the end of the heat tube (farthest from the piston). Its function depends on a the time delay for pressure to increase once temperature is changed as discovered by Tailor in the 60's.
The Pulse Tube or Lamina Flow engine has a longer tube, a regenerator, a pulse tube section and many times a constrictor. The regenerator is located at the farthest point from the piston and heat is applied at the interface of the regenerator and the pulse tube. At the opposite end of the pulse tube next to the piston is where the restrictor is located if needed. This engine functions due to the temperature differential across the pulse tube sets up a standing wave that produces the motive force.
The design discussed here at first doesn't look like either of these descriptions and is what contributes to the confusion. This disign contains a tube within a tube ultimately folding the pulse tube engine in half. Even thouh it looks like the tube is heated at the end like the thermal lag engine, it is actually being heated in the middle due to the folding. In earlier posts by the OP he references the use of a restrictor. Even though lated designs by the OP indicates both the restrictor and the regenerator material are no longer used, their function still exist. When tuned properly this engine can use the pointed part of the inner tube as a functioning restrictor. Many people have built a small test tube engine and made it function without regenerator material. This is because the empty tube can act as a regenerator and the same thing occurs in the OP's engine. The outer tube in this engine is the pulse tube and the inner tube is the regenerator. The length of the tubes are also a dead give away that this is not a TLE as Tailer describes and would cause far too much dead space for it operate as a TLE.
Re: large lamina flow build
I vote this engine derwood designed is the best hot air engine I've ever seen. It's so impressive. I wish he would prony brake it to test the power. I want one.
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tibsim
Re: large lamina flow build
Lamina flow experiment:
https://www.youtube.com/watch?v=nqtP78Kjlns
https://www.youtube.com/watch?v=nqtP78Kjlns
Re: large lamina flow build
After so many here contributed. Gave away all their ideas and experience to help you. Some attitude.
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Sockmonkey
- Posts: 50
- Joined: Wed Jul 31, 2019 5:32 pm
Re: large lamina flow build
I suspect that in the early version that worked without a flywheel, the piston was acting as a heat sink/radiator.
Re: large lamina flow build
Interesting idea, or question; how these engines can run without a flywheel.
I've puzzled over that myself. Going back in the thread I assume you are referring to this video:
https://youtu.be/pOHJLW1osSM
My thought is that heat travel by conduction is probably much too slow compared to the rpm of the engine.
I've more or less settled on the conclusion that these engines don't need a flywheel or a heat sink/radiator.
What if the piston were constructed of some non-heat-conducting material? Would the engine still run without this potential heat sink, or rather, would it run with this suspected heat sink eliminated?
There is some additional speculation on this other thread:
viewtopic.php?f=1&t=2545
Towards what is currently the end of that thread, I posted some additional video examples of various Stirling engines running with no flywheel:
https://youtu.be/bOL6QVnQQzc
I've puzzled over that myself. Going back in the thread I assume you are referring to this video:
https://youtu.be/pOHJLW1osSM
My thought is that heat travel by conduction is probably much too slow compared to the rpm of the engine.
I've more or less settled on the conclusion that these engines don't need a flywheel or a heat sink/radiator.
What if the piston were constructed of some non-heat-conducting material? Would the engine still run without this potential heat sink, or rather, would it run with this suspected heat sink eliminated?
There is some additional speculation on this other thread:
viewtopic.php?f=1&t=2545
Towards what is currently the end of that thread, I posted some additional video examples of various Stirling engines running with no flywheel:
https://youtu.be/bOL6QVnQQzc
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Sockmonkey
- Posts: 50
- Joined: Wed Jul 31, 2019 5:32 pm
Re: large lamina flow build
Yeah, like you said earlier, if the stroke of the piston is long enough to let the cylinder pressure drop below atmospheric, outside pressure pushes the piston back in. Effectively a one-stroke engine. Well, one and a half since the up-stroke would be weaker than the down-stroke.
Re: large lamina flow build
What I find rather amazing also is how, when getting started, this pushing the piston back down the cylinder will occur with a flywheel resulting in a kind of rocking back and forth, until the engine gets over the "hump" so to speak.
This drawing back in, or pushing back in, takes place even against the momentum or inertia of a heavy flywheel.
Take this video for example:
https://youtu.be/_5fv-xFuozs?t=196
This drawing back in, or pushing back in, takes place even against the momentum or inertia of a heavy flywheel.
Take this video for example:
https://youtu.be/_5fv-xFuozs?t=196
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Sockmonkey
- Posts: 50
- Joined: Wed Jul 31, 2019 5:32 pm
Re: large lamina flow build
Since the end of the tube filled with steel wool is acting as kind of heat reservoir, does that part have to be tube shaped instead of a big sphere or something?
Re: large lamina flow build
I'm not entirely sure about the theory behind the steel wool. I'm not sure it is actually a heat reservoir.
This type of engine is called laminar flow. Why? What exactly does that mean and how is laminar flow produced? What purpose does it serve?
I came across this interesting video on how to make a laminar flow nozzle for a garden hose.
What I find intriguing is this laminar flow water jet nozzle packed with dish scrubbers and straws and with a narrow orifice, quite resembles a laminar flow Stirling with it's wad of steel wool and similar narrow orifice.
Perhaps the purpose of the steel wool has nothing to do with heat, but is rather a means of eliminating turbulence so that the piston is driven by a focused jet of air through the nozzle.
https://youtu.be/o5L6W0YoAd4
As far as your question, I did see a demonstration of dropping a tight fitting weight into a jug with a long neck.
The weight bobbed up and down in the neck of the jug, which also reminded me of how these engines behave, but I haven't found the video. I don't actually know the answer to your question though.
Another "explanation" is this is a kind of thermoaccoustic Rijke tube:
https://youtu.be/pncG3lJUOdY
but I've never knows these type of Stirling engines to produce any audible sound, so personally I tend to discount the superficial resemblance and favor the laminar flow explanation. A Rijke tube and/or actual thermoaccoustic device (Hofler tube) does not need a narrow orifice. Infact, I'm rather certain the presence of an orifice and piston in the tube, as well as the end of the tube (Stirling engine) being completely closed would nullify any possibility of an accustic effect.
Hofler tube, (or actual thermoaccoustic "engine" -not a Stirling, though there is a superficial resemblance)
https://youtu.be/7WHTaRdIugA
My guess is a big sphere would just introduce dead air space, reducing the efficiency of the engine, but who knows? Maybe like the weight dropped down the neck of a big jug, it might actually act as a kind of air spring. Not sure anyone has ever tried it.
This type of engine is called laminar flow. Why? What exactly does that mean and how is laminar flow produced? What purpose does it serve?
I came across this interesting video on how to make a laminar flow nozzle for a garden hose.
What I find intriguing is this laminar flow water jet nozzle packed with dish scrubbers and straws and with a narrow orifice, quite resembles a laminar flow Stirling with it's wad of steel wool and similar narrow orifice.
Perhaps the purpose of the steel wool has nothing to do with heat, but is rather a means of eliminating turbulence so that the piston is driven by a focused jet of air through the nozzle.
https://youtu.be/o5L6W0YoAd4
As far as your question, I did see a demonstration of dropping a tight fitting weight into a jug with a long neck.
The weight bobbed up and down in the neck of the jug, which also reminded me of how these engines behave, but I haven't found the video. I don't actually know the answer to your question though.
Another "explanation" is this is a kind of thermoaccoustic Rijke tube:
https://youtu.be/pncG3lJUOdY
but I've never knows these type of Stirling engines to produce any audible sound, so personally I tend to discount the superficial resemblance and favor the laminar flow explanation. A Rijke tube and/or actual thermoaccoustic device (Hofler tube) does not need a narrow orifice. Infact, I'm rather certain the presence of an orifice and piston in the tube, as well as the end of the tube (Stirling engine) being completely closed would nullify any possibility of an accustic effect.
Hofler tube, (or actual thermoaccoustic "engine" -not a Stirling, though there is a superficial resemblance)
https://youtu.be/7WHTaRdIugA
My guess is a big sphere would just introduce dead air space, reducing the efficiency of the engine, but who knows? Maybe like the weight dropped down the neck of a big jug, it might actually act as a kind of air spring. Not sure anyone has ever tried it.