Hei again!"
I have been trying to get more rpm of my last stirling, but i wont go over 550 rpm, i tryed to remove one round of the steelwool, cause i was thinking that i was to thight,but after i had removed a little rockwool,it did not start,so i am thinking, that a tin can piston will give me more RPM???..
[video 425,350]https://www.youtube.com/watch?v=1Fuvn4340uE[/video]
So now i will try to use a shorter piston"3.0/3.5cm", and see if i get more rpm, i have teste about 4 differents cranks!.the cylinder is 8-8.5cm
Displacer gap too big?,now with 2 cylinder building
Displacer gap too big?,now with 2 cylinder building
Last edited by larsinist on Fri Apr 04, 2014 3:41 pm, edited 1 time in total.
Re: Displacer gap too big?
it needs to be tight, when a roockwool piston is used, ,now i will try a 10,5 cm can, cause i think longer can/stroke, will give me more rpm...but will a tin can piston be better faster than roockwool??
Re: Displacer gap too big?
Hey Lars, how much empty space is there under the power membrane? Just a thought. Someone here said if you want RPM, go after power. Another thought, is the function of displacer is to displace air from hot to cold and back; the function of steel wool is regenerator, i.e. allow the cold air traveling through to warm up, and vice versa for the cold end. So an ideal regenerator would have infinite surface, while ideal displacer would be near zero mass and fill spece required to displace the volume of air from hot end to the cold; looking at it from this point, the displacer gap is a tradeoff between friction, regenerative capacity, mass, and displacement volume.
I would test for each of those separately, for example regenerative capacity would be poor if your engine slows down when it is fully warmed up. Displacement volume would affect the power - or the length of power piston stroke when disconnected from the shaft. In general, they say that max rpm is dependent on the amount of air inside the engine that can be heated or cooled over shortest period of time.
Weight of displacer - and other mechanical losses, like friction, - can also be isolated one by one.
I would test for each of those separately, for example regenerative capacity would be poor if your engine slows down when it is fully warmed up. Displacement volume would affect the power - or the length of power piston stroke when disconnected from the shaft. In general, they say that max rpm is dependent on the amount of air inside the engine that can be heated or cooled over shortest period of time.
Weight of displacer - and other mechanical losses, like friction, - can also be isolated one by one.
Re: Displacer gap too big?
i have 3cm under the power membrane/balon so i think it will be better with a 10,5 cm cylinder, i am building it now..
Thanks for answer!!
Thanks for answer!!
Re: Displacer gap too big?
think i got about 450-550 rpm now, i will post a video later!!
i have not tryed it on a burner, i think i will get more rpm on alcohol[video 425,350]https://www.youtube.com/watch?v=CGFGPp3 ... e=youtu.be[/video]
i have not tryed it on a burner, i think i will get more rpm on alcohol[video 425,350]https://www.youtube.com/watch?v=CGFGPp3 ... e=youtu.be[/video]
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: Displacer gap too big?
Hi,
Your engines are getting better and better everytime! I see you're learning, and building, very fast!
I've just started building a new popcan Stirling Engine, let's see what speed i can get. I've built one 2 years ago, but with fishing line etc.
now it's getting connecting rods instead of fishing line, aluminium top, to avoid rust, another water cooling bucket, bearings etc.
Keep sharing your progress!
Your engines are getting better and better everytime! I see you're learning, and building, very fast!
I've just started building a new popcan Stirling Engine, let's see what speed i can get. I've built one 2 years ago, but with fishing line etc.
now it's getting connecting rods instead of fishing line, aluminium top, to avoid rust, another water cooling bucket, bearings etc.
Keep sharing your progress!
Re: Displacer gap too big?
Thank you, now i am in building of my 2 cylinder, and i shall use 2x 10,5 cm cylinder lenght "from a coke can",and i shall ise a 3.5cm long displacer,and long rods..so i think those measurements will be good??,what do you think?..
i can make a building tread in the forum!
will longer rods give more rpm,??i am thinking of the sideways angle on the rod.cause it get smaller when i am using longer rods..
i can make a building tread in the forum!
will longer rods give more rpm,??i am thinking of the sideways angle on the rod.cause it get smaller when i am using longer rods..
Re: Displacer gap too big?
but i am open for anything, i should build the 2 cylinder for torq, but it is much more fun to build if for RPM,so my 10.5cm lenght on them cylinders will not give so much rpm..so am need to think agani!!!
what do you mean??..will a much shorter stroke give me alot of them rpms?
got 580 rpm at the maximum with these measurements!!
And i think i could get more RPM if i add one more hose from the sylinder head to the diaphgram!!
what do you mean??..will a much shorter stroke give me alot of them rpms?
got 580 rpm at the maximum with these measurements!!
And i think i could get more RPM if i add one more hose from the sylinder head to the diaphgram!!
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: Displacer gap too big?
Hi,
About the rods: what you say about the movement to the sides: longer rods give a lower 'sideways angle'. But longer rods give also more weight, i think the best point is somewhere in between. Too short causes to much friction, but to long isn't also good i think. I don't know for sure, the only way is to test it out!
a shorter stroke gives higher RPM's. Have you looked at my other post in another thread of you? when your cylinder is 10 cm, you can make a stroke of 2 cm (displacer = 6 cm minus clearance) When you make a 1.5 cm stroke ( cm. minus clearance displacer) it will run faster, with a lower torque.
From what i understand the total cylinder hight isn't that important. When you have longer cylinders, the hot and cold side are more separated. Maybe someone else does know?
I don't think more tubes is necessary, i think you've enough there.
About the rods: what you say about the movement to the sides: longer rods give a lower 'sideways angle'. But longer rods give also more weight, i think the best point is somewhere in between. Too short causes to much friction, but to long isn't also good i think. I don't know for sure, the only way is to test it out!
a shorter stroke gives higher RPM's. Have you looked at my other post in another thread of you? when your cylinder is 10 cm, you can make a stroke of 2 cm (displacer = 6 cm minus clearance) When you make a 1.5 cm stroke ( cm. minus clearance displacer) it will run faster, with a lower torque.
From what i understand the total cylinder hight isn't that important. When you have longer cylinders, the hot and cold side are more separated. Maybe someone else does know?
I don't think more tubes is necessary, i think you've enough there.
Re: Displacer gap too big?
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Re: Displacer gap too big?
should i have a suppert bearing/sealing for the dispencer rod?,.cause i only have one now.and there will be a little sideways movement there.and inserting a new seal/bearing will make the cylinder thighter also..what you think here??
Re: Displacer gap too big?,now with 2 cylinder building
I might be wrong, But I don't see any flexible joint in the displacer rod, are you relying on the bending of the rod to allow it to follow the crank, or are you using a Scotch yoke instead of a normal big end.
Ian S C
Ian S C
Re: Displacer gap too big?,now with 2 cylinder building
Ian S C
Thank you for your reply,i am not finished yet with them rods, i will shorten them down today,and then i will mount a flexible joint.
i am thinking that i will have the flywheel in the middle,and i will use 4 ballbearings,is that to much?
Thank you for your reply,i am not finished yet with them rods, i will shorten them down today,and then i will mount a flexible joint.
i am thinking that i will have the flywheel in the middle,and i will use 4 ballbearings,is that to much?
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Triangle.Stirling
- Posts: 133
- Joined: Mon Sep 09, 2013 8:29 am
Re: Displacer gap too big?,now with 2 cylinder building
hi,
Nice progress! It's really nice!
two questions:
- the upside of your cylinder, is that simply a bottom of a can pressed down into another can? just a thight fit, no glue?
- like to see how you do the flexible joint. i'm searching for a way to do it by my own popcan engine.
Regards,
Krijn
Nice progress! It's really nice!
two questions:
- the upside of your cylinder, is that simply a bottom of a can pressed down into another can? just a thight fit, no glue?
- like to see how you do the flexible joint. i'm searching for a way to do it by my own popcan engine.
Regards,
Krijn
Re: Displacer gap too big?,now with 2 cylinder building
Hei Triangle.Stirling and Thank you for good words!!!!!!!!!!!!!!!!.
The bottom is just a can pressed down,i just made a flange with a complete coke can,and then i let it stay there fore 1 hour, to make the flange.i have used some glue to make them cylinders thight, i will build some more today, but i dont have the fly-wheel shaft..so i think i will use some more days to make this finished
special thanks again to Krijn and Ian S C for giving me info
Best regards:Lars Kristian Henriksen
The bottom is just a can pressed down,i just made a flange with a complete coke can,and then i let it stay there fore 1 hour, to make the flange.i have used some glue to make them cylinders thight, i will build some more today, but i dont have the fly-wheel shaft..so i think i will use some more days to make this finished
special thanks again to Krijn and Ian S C for giving me info
Best regards:Lars Kristian Henriksen