Morgan
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Cascading Vacuum Effect
I was watching this video of a steam vacuum, a kind of a
Newcomen Atmospheric Engine if you will. Anyway, it's curious how the water slowly travels up the neck a few inches and then the steam/vapor suddenly
collapses as if all the little molecules were a transitor switching from one state to another. A few things came to mind. Is there some cavitation of
the water suddenly in the neck? Would some of the mist/spray from the erupting cavitation further the effect if such an occurrence took place? I tried
to freeze the clip frame by frame to see what might be happening.
Would you think cold water would work better than warm? Does one cavitate faster than the other? How does the temperature drop affect the
communication between the molecules in the cylindrical vessel? Does a wave propagate at some random or specific spot, say by the colder liquid water?
How might a stiff glass bottle differ from a thin plastic bottle?
Steam-Powered Vacuum
http://www.youtube.com/watch?v=0pNfADJlr4g#t=44s
Plastic bottle variation/cold water didn't work for him
http://www.youtube.com/watch?v=Tm3f1MfrWdM
Shatter beer bottles: Bare-handed bottle smash
http://www.youtube.com/watch?v=77gWkl0ZUC8#t=1m39s
http://www.egr.msu.edu/~lira/supp/steam/
[Edited on 18-4-2013 by Morgan]
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Morgan
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I tried a meter long quartz tube with rubber stopper in one end and boiled some water in it with a propane torch, the kind that has a piezo starter
and more ambitious flame. No matter if I heated a large length or short length of water to a boil, poured it out quickly and submerged it did anything
rapid occur. I was hoping the vacuum would cause the H2O to shoot up the tube, knocking the rubber stopper out and launch a column of water.
I might try submerging the whole tube at once at as much of an angle while still keeping the rubber stopper above the water line. Or maybe spray water
on it to cool it. Today's trial was with 3mm wall thickness. I have some thinner wall as well.
I love quartz because it has yet to crack on me even heated to a red heat. Thin sheets of quartz heated to a red heat can be dipped in water without
cracking.
Maybe though the best way to create the collapsing effect is to use a large volume in a spherical shape.
[Edited on 19-4-2013 by Morgan]
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Twospoons
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I think its just the change in liquid surface area, exacerbated by the jet that forms as the flow rate increases. I'd expect the effect to be more
pronounced with cold water, but you'd risk thermal shock breaking the bottle.
Helicopter: "helico" -> spiral, "pter" -> with wings
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Morgan
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It's mysterious how cold water defeated the cascade effect in the instance below. There's something intriguing how that's playing out, how this
peculiar nature of sudden condensation is counter-intuitive/suppressed for whatever reason. I think it's worth asking why. Mysteries are sometimes
great teachers. The understanding/the solution to this cold water/plastic bottle result will turn out to be something simple, but it's not apparent.
Plastic bottle variation/cold water didn't work for him
http://www.youtube.com/watch?v=Tm3f1MfrWdM
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