It helps to know what is actually going on inside one of these engines.
After running my laminar flow, thermoacoustic, thermal lag, or whatever irs supposed to be engine, with the "inner tube" as its being refered to here made of
wood.
The wood sometimes, after the engine has run for a while starts to
smoke.
Pretty obviously that passageway is being subject to some very high temperatures.
This will rather quickly cause the engine to stall. The smoke and wood resin gums up the piston and cylinder like chewing gum, then it will have to be cleaned.
The extreme heat also tends to degrade the silicone O rings.
With all that, however, the power piston stays cool. Even after running several minutes with a styrofoam sleeve covering the power piston, it has never become hot to the touch, not even warn really.
Anyway, what was interesting about the passage through the wood starting to smoke and the engine stalling is that it provided a very clear view of the air flow out of the orifice.
Unfortunately, by the time I noticed this and grabbed my phone the smoke was already starting to clear so it cannot be seen as clearly in the video, but it was most definitely a long smooth laminar flow streaming straight into the steel wool.
https://youtu.be/Yt5CYSXK3A8?si=OE8E2VtT75hQ5vS3
I would need to do more testing to be sure, but experimenting a little, the laminar flow extends into the hot cylinder only so far before breaking up.
Progressively shortening the steel wool, I had a difficult time trying to start the engine if the steel wool was too far for the laminar stream to reach.
I'd have to assume that a similar stream flows out from the opposite end of the orifice.