Resonant and Non-Resonant stirling engine

Discussion on Stirling or "hot air" engines (all types)
Post Reply
msb
Posts: 8
Joined: Mon Feb 15, 2010 1:41 pm

Resonant and Non-Resonant stirling engine

Post by msb »

Hello to all friends
Can anyone give me a good definition about resonant and non- resonant stirling engine?
Tom Booth
Posts: 4669
Joined: Tue Nov 07, 2006 2:03 am
Location: Fort Plain New York USA
Contact:

Re: Resonant and Non-Resonant stirling engine

Post by Tom Booth »

msb wrote:Hello to all friends
Can anyone give me a good definition about resonant and non- resonant stirling engine?
Hi,

I guess this is just my opinion at this point as I haven't really found anyone who agrees with the idea... but IMO, there isn't really any such thing as a "resonant" or "thermo-acoustic" Stirling engine.

Apparently at some point in time someone made the observation that a hollow tube has acoustic / resonant properties.

This however is true of any and all hollow objects and is the basis of many musical instruments - bells, drums, guitars, violins etc.

All resonate at various frequencies due to "standing waves".

Concluding that just because a hollow tube CAN HAVE acoustic properties under certain circumstances - that this is what actually drives a Stirling engine - in my mind, is something like concluding that just because my wind chimes are made out of different size metal tubes suspended by strings and the plumbing in my house is also made out of metal tubes cut to various lengths suspended by pipe hangers, this must be why I can take a shower in the morning - because my plumbing pipes are singing and vibrating at a sound frequency that causes changes in the water pressure and so the water flows from the well to the shower head due to the changes in pressure caused by the sound. The pump in my basement doesn't really have anything to do with it!

I've been watching a lot of You Tube videos lately of various Laminar Flow or so-called "Thermo-acoustic" Stirling Engines and I've noticed that several You-Tube movie makers ave commented on the fact that the piston ("free piston" type) sometimes has a tendency to start banging into the "choke", so they installed a rubber "bumper" to take care of the problem.

Could this be because - due to the air in the engine expanding and doing work it is actually giving up more heat than it is taking in and so contracting more than it is expanding - banging into the choke as a result ?

I guess this is just my own pet idea of how a Stirling engine works at the moment (Heating of the gas followed by the gas expanding and doing work resulting in cooling of the gas) but for whatever its worth, I don't think that there is really any such thing as a "resonant" Stirling engine. This is just a popular myth that got started somehow for lack of any better explanation as to how a laminar flow Stirling engine actually works.
Post Reply