[Geysers] Re: geysers

Fri Jan 14 07:17:59 PST 2005

Amy and Alan and all - We made a geyser for my son's science fair last
year.  Worked very well.  We made our test simple - basically, what is
(observationally) the difference between a "fountain"-type geyser and a
"cone"-type geyser (all with the same plumbing and heat source, of
course)?  The only thing we adjusted was the water level at the outlet.

Ours was strictly an outdoor model, using a propane stove as the heat
source and a very sturdy heavy-based 1-liter Erlenmeyer flask as the
heating vessel.  A copper tube of the type used for refrigerator coils
(available at hardware stores cheap and not at all fragile) was used as
the vent, through a drilled-out rubber stopper atop the flask.  The bottom
of the vent was placed about 1/2 to 1 inch from the bottom of the flask,
in order to allow most of the water to erupt, but so as to not totally dry
out the bottom of the flask at eruption's end.  We used a tupperware-clone
2-quart basin at the top with a hole in the center for the vent, sealed
with plumber's putty.  About 3.5 feet from vent bottom to vent top.  A
large strong tripod over the stove held the whole shebang upright.  We
used a heat diffuser made of heavy aluminum under the flask; ultimately,
this was not the best choice, as even a small propane stove was hot enough
to melt the aluminum.  One wants to avoid "hot spots" in the glass of the
beaker, and it is better if the flask can be suspended over the flame.  As
it was, our beaker developed *tiny* radial cracks along the outer edge of
the base (which did not seem to compromise the pressure seal).  

However, the whole apparatus survived more than three dozen repeats, and
still is operable for the occasional neighborhood demonstration.  We get
spectacular play up to 10 feet above the vent when used as a cone geyser,
and big 3-foot splashes when used as a fountain geyser.  It is amazing how
well this simple model seems to duplicate real geyser behavior, including
pre-play overflow, steam bubble collapse, water and steam phase.  Fun!

A big thank you to Alan - his website helped us a great deal, especially
to nail down specifics of the model last year.

Bruce Jensen
************

--- Alan Glennon <glennon at umail.ucsb.edu> wrote:

> --- original message  --- 
>   From: AMYKARMAK at aol.com 
> 
> 
>   Alan-  We came across your web site when we were searching for
> additional info. on geysers for my sons' (3rd grade)  science fair
> project.  I thought that maybe you could offer some suggestions to help
> us out. . . My son found an experiment on www.exploratorium.edu that
> sparked his interest in geysers and, therefore, has lead him to want to
> do his science fair project on geysers. We can't, however, fiqure out a
> question and hypothesis (prediction) to base the project on-  Do you
> have any opinions or suggestion for us?  Any advise or referrals to
> other web sites would be so helpful~ Thank you.
> -------------------
> Amy,
> 
> I forwarded your email to the other geyser observers; perhaps they have
> comments or could correct any conceptual or logic problems in my
> suggestions... hopefully, my rambling, off-the-cuff answer, will provide
> you some ideas...
> 
> Coming up with testable geyser hypotheses for science fair projects can
> be a tricky -- particularly, since it tends to be hard to build a
> realistic geyser model on which to conduct tests; it's quite dangerous
> too. However, assuming you're thoughtful and careful, once the geyser
> model is built, it's lots of fun.
> 
> When I make a model geyser, I tend to make variations of the following:
> http://www.wyojones.com/science_fair_projects_and_geyser.htm
> 
> Again, if you build one of these things--> be very, very careful!
> 
> Once built, the model will lead to questions like:
> Is there a relationship between the length (depth) of the geyser's tube
> and the eruption height?
> How does the outlet location of the geyser's reservoir affect the
> eruption height or duration (where the bottom of the tube is located in
> the beaker)?
> What happens when I use two vents instead of one, what if they're at
> different levels on the top or bottom? Note to geyser people: I made
> wonderful model of Whirligig experimenting with this question.
> 
> In my university lab, I was able to make minor, intermediate, and major
> eruptions by connecting two models; of course, that takes more and more
> glassware.
> 
> It may be possible to do something similar with carbonated water, but
> I've never tried. That'd be a lot safer, and then you could use plastics
> and standard-type tubing. It would be a delicate balance between
> overlying water pressure and CO2 wanting to escape. If nothing else,
> when building a model, it's easy to see why geysers are so rare. Minor
> changes in the model (particularly vent diameter) make the difference
> between violent eruption and gentle overflow. 
> 
> In fact, if you have a way to measure the pressure coming out from a
> waterhose, you could look at pressure versus orifice size and the
> resulting "eruption" height. Without measuring pressure, you could hold
> pressure constant and if you could somehow measure the size of the
> waterhose outlet (and change it using various spigot sizes), you could
> track how orifice size changes the height water is expelled. Since we
> can estimate Old Faithful's orifice size and height, we could backtrack
> and get an estimate of its pressure. Of course, if you don't have a way
> to measure the pressure, you could keep it constant and obtain an answer
> like: Old Faithful has 10000 times more pressure than my waterhose. A
> statistician would be unhappy with such a large extrapolation -- but of
> course, there are small geysers too. See my article on El Tatio geysers
> -- I'll make the full text available in pdf for the next day or two at
> http://www.uweb.ucsb.edu/~glennon/travel/tatio.htm  I describe quite a
> few geysers; look for descriptions of the vents and their heights.
> You'll probably be able to find a geyser that has a fraction of a
> typical waterhose's pressure.
> 
> A constriction often is present within the geyser's plumbing geometry.
> In the glassware model, the tube itself accounts for the constriction
> out of the reservoir. Thus, the constriction is also the vent of the
> geyser. If you use a rubber tube or waterhose (and a clamp of some
> sort), how does the constriction's distance from geyser vent change the
> eruption?
> 
> Anyway, those are a couple of random ideas...
> 
> Good luck -- be careful -- and if you discover something neat, let me
> know.
> ~Alan
> 
> 
> J. Alan Glennon, Ph.D. Student
> NCGIA/Department of Geography
> University of California, Santa Barbara
> Santa Barbara, CA 93106
> glennon at umail.ucsb.edu
> > _______________________________________________
> Geysers mailing list
> Geysers at wwc.edu
> https://mailman.wwc.edu/mailman/listinfo/geysers
> 

=====
Cheers,
Bruce Jensen
~~~~~~~~~~~~

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