Laminar flow fountain Nozzles?
Glenn Ashmore
How do you build a laminar flow fountain nozzle? By that I mean like
the famous jumping fountains at Epcot and the big one in the Tiki Room.
I figured out how they get the clean cutoffs on those slugs of water
in the jumping fountain but I just don't see how the laminar flow works.
--
Glenn Ashmore
I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com
Jeff Wisnia
IIRC, the "laminator" is a bundle of small straight tubes, though I don't
have any design info. I think the basic concept is to remove the turbulence
always present in water flowing through a large pipe by separating the water
into a number of skinny columns and then combining those columns just before
the fountain nozzle outlet.
If you could sneak a look at a commercial one you could probably see how to
make a DIY one without a lot of trial and error.
Jeff
--
Jeff Wisnia (W1BSV + Brass Rat '57 EE)
"Success is getting what you like; Happiness is liking what you get."
Ernie Leimkuhler
<ru...@bellsouth.net> wrote:
> I vaguely remember us tossing this subject around a few years ago.
>
> How do you build a laminar flow fountain nozzle? By that I mean like
> the famous jumping fountains at Epcot and the big one in the Tiki Room.
> I figured out how they get the clean cutoffs on those slugs of water
> in the jumping fountain but I just don't see how the laminar flow works.
We used to build these at the Hydromechanics Lab at Purdue.
We would just take a piece of 3" PVC pipe and fill it full of drinking
straws.
If you need a small jet then just neck down the pipe after the lamilar
filter, but the reducer fittings have to have a very precise sine wave
curve to them to prevent cavitation, and maintain the lamilar flow.
It works very well.
BTW - The way they make the water jump at EPCOT isn't by turning the
water on and off, but rather by turning off a deflecting jet of water
for a brief moment.
In other words the lamilar flow jet is going all the time, but most of
the time there is a second water jet that deflects it into catch tube.
John Flanagan
<jwi...@conversent.net> wrote:
>Glenn Ashmore wrote:
>
>> I vaguely remember us tossing this subject around a few years ago.
>>
>> How do you build a laminar flow fountain nozzle? By that I mean like
>> the famous jumping fountains at Epcot and the big one in the Tiki Room.
>> I figured out how they get the clean cutoffs on those slugs of water
>> in the jumping fountain but I just don't see how the laminar flow works.
>>
>> --
>> Glenn Ashmore
>>
>> I'm building a 45' cutter in strip/composite. Watch my progress (or lack
>> there of) at: http://www.rutuonline.com
>> Shameless Commercial Division: http://www.spade-anchor-us.com
>
>IIRC, the "laminator" is a bundle of small straight tubes, though I don't
>have any design info. I think the basic concept is to remove the turbulence
>always present in water flowing through a large pipe by separating the water
>into a number of skinny columns and then combining those columns just before
>the fountain nozzle outlet.
>
>If you could sneak a look at a commercial one you could probably see how to
>make a DIY one without a lot of trial and error.
This could probably also be done by placing a screen (mesh to be
determined) at the inlet of a smooth and straight tube of a certain
length with a smooth mouth at the outlet. The screen produces a
turbulence of small dimensions which smooth out before getting to the
mouth of the outlet. Wind tunnels use the same tecnique. IIRC.
John
Please note that my return address is wrong due to the amount of junk email I get.
So please respond to this message through the newsgroup.
Glenn Ashmore
Ernie Leimkuhler wrote:
> BTW - The way they make the water jump at EPCOT isn't by turning the
> water on and off, but rather by turning off a deflecting jet of water
> for a brief moment.
>
> In other words the lamilar flow jet is going all the time, but most of
> the time there is a second water jet that deflects it into catch tube.
I figured that out by sneaking up on one and timing my peek just right. :-)
nobody
cap one end, which will now be the 'bottom'.
tap a hole through the cap for a hose-bib attachement.
staple scotch-brite pads together end to end, and roll them tightly until
you have a roll big enough that it fits very snugly into
the 10" pvc. you will now have a 'plug' that you shove into the pvc, all the
way to the bottom. when you look into the pipe, you should see the 'side' of
your roll....the swirly part.
you need to keep the plug at the bottom. take a just-smaller diameter piece
of pipe/fitting/etc, (maybe 1-2 inches long) and criss cross one end with
wire. shove this in on top of the plug, and secure in place with
screws/glue, depending on how close the fit is.
**********here comes the tricky part.*******
the business end of a laminar nozzle is a plate with a hole in it. i use
lexan, because it is relatively hard, and will not corrode. 3/8" lexan
sheet, cut 2-3 inches larger that the pipe diameter.
the most important thing is the hole.
you need a countersunk hole, right in the middle.
if you are feeding the nozzle with a hose, go with a 3/4" to 1" hole. drill
smaller, then ream the hole to size.
the hole must be VERY clean and straight.
you then countersink the hole about 90%, leaving only a small bit of the
original hole diameter, follow?
this also needs to be very cleanly done.
do not chamfer the non-countersunk side of the hole!
must be very sharp edges.....use an x-acto to cut away any bur that may
remain, but leave a sharp, square edge.
drill 4 1/4"holes in a pattern just larger that the diameter of the pipe.
silicone the end of the pipe, and center and adhere the plate so that the
hole is in the center, and the countersunk side of the hole is facing OUT .
it will not work at all if the counterunk side is IN .
use 4 pieces of 1/4" all-thread, and another piece of plate (with the same
mouting holes) to 'sandwich' the pipe between the two plates, thus very
positively attaching the lexan plate to the end of the pipe.
--the scotchbrite is a flow straightener.
--the purpose of the countersunk hole is to minimize the amount of
turbulance by minimizing the amount of material the water is in contact
with.
(if you just drill a hole in the lexan, you will get a fairly straight flow,
but with the countersink you get that 'glass-rod' look you are after.)
--the reason for using a thick plate and countersinking as opposed to just a
thinner plate is that the plate will bow out under pressure, and you no
longer have a straight hole.
have built many of these, many different variations...this one is simple.
good luck-
-nobody
"Glenn Ashmore" <ru...@bellsouth.net> wrote in message
news:3EEF90D...@bellsouth.net...
Jim
>
> How do you build a laminar flow fountain nozzle? By that I mean like
> the famous jumping fountains at Epcot and the big one in the Tiki Room.
> I figured out how they get the clean cutoffs on those slugs of water
> in the jumping fountain but I just don't see how the laminar flow works.
I just posted the info about this a few months ago, (and also in 1995)
having had experience building them, I don't know how to post a link
to my message, if you want to search the group it's under a message
called: "OT : Water Fountain Valves" but I'll repost it here too
(and it will show up 12 hours after I posted it too, thanks
Google....) :
I've built them before. Well...knock offs of them. (not for sale)
the one's you have seen are manufactured by WET engineering. The
patents are really helpful in explaining how they actually work.
I initially thought that some hi-speed valves would work too....they
don't.
Its been many years and I don't have the patent numbers handy,
++++++++++++++
(update June 2003, here's one patent number, 4,795,092 look it up
for a more explicit explanation:)
++++++++++++++
but there are basically 2 parts to this system:
1: "laminizing" the water: Any water that is pumped to the device
runs through pipe and it causes turbulence. You have to remove this
turbulance, creating a "laminar flow" of the mass of water.
The water enters the first stage: the base of a cylinder that is about
18"-24" diameter. It enters at a Tangent, or as much of one as
possible, this creates basically a swirling action in the bottom of
the cylinder. Now that the mass of water that came from , say a 1"
pipe is now in a 18" diameter pipe, it's flow rate is greatly reduced
and the mass of now swirling water slowly proceeds to fill the
Cylinder.
It next encounters a screen and then a section of open-cell foam that
essentially removes all the "swirling" from the mass of water.
Then it enters the packed sets of tubing or straws (which seems to be
all that anyone remembers about it), all the water mass is divided up
now into little tubes, but the flow rate is VERY slow, remember, the
the larger tube (the Cylinder) that this is all running through is 18"
diameter. There is a bit of math involved where you want to keep the
flow rate in the tube below the Reynold's Number (sort of the line
where laminar flow becomes turbulent...)
So then the water emerges from these clustered tubes (they are maybe
12" long) and the water gathers back together in an empty chamber
maybe 2" deep, another screen knocks out any remaining trace of
turbulence and now you have a cylindrical block of water with NO
turbulence moving to the end of the cylinder.
The end of the Cylinder has an exit port. The one's I made were 1/2",
but you could go to 3/4" or 1", the most important part of this "port"
is that is has a "knife edge". In other words, you don't just drill
a hole in the end of the cylinder, if you did, you would create a very
short tube and the water running through it would get turbulent again.
The water that exits this port is clear and wants to stay together.
the "fountain" continously operates, the water is ALWAYS moving out of
this port.
That's the first part
Now Part 2: Creating the on/off
The nice laminar stream of water that you have just created now goes
through another cylinder stacked on the end of the first one. The
second cylinder has a hole that allows the water to exit and stream
out. This second exit port is maybe 50% larger than the water stream
and the water does NOT touch it.
To turn the stream on and off, you Do NOT run the water stream through
a Valve. You DIVERT the stream. The ones From WET Engineering do it
with a solenoid valve that will blast a stream of high pressure water
at the laminar stream, pushing it off to the side and preventing it
from exiting the final port in the second cylinder. This water drains
back into the water supply. When the solenoid valve shuts off, it
stops disrupting the clear laminar stream and the stream is allowed to
exit the system. Rapidly diverting the water on and off creates the
illusion that the stream is turning on and off, but in reality, it is
running all the time.
All this information is in the patents filed by WET.
I did not use the solenoid valve water diverters on mine, I used a
pneumatic cylinder with a flat SS plate on the end. When engaged, the
laminar stream would hit the plate and fan out 360 degrees and exit
the system. When it was in this position, no water would exit the
system. But the stream was flowing at all times. When the Pneumatic
Cylinder was rapidly retracted, the water was allowed to exit.
Engaging the Pneumatic Cylinder again would cause the SS plate to slam
into place and block the stream.
It's quite interesting and took quite a while to figure out and
perfect. If you look closely at the ones that WET engineering has
operating, the beginnings and endings are not "perfect", there is a
"knuckle" of water that leads and few trailing drops or spray at the
end. Very slight but noticable.
I was able to tune mine so that, at the time (8-9 years ago), I had
(what I thought) was a better looking stream with a better and more
positive cutoff on the head and tail.
Unfortunately, the addition of the pneumatic cylinder just adds more
complexity to the initial elegant design and is another point of
failure for a device that is expected to run for long periods of time.
If anyone wants to email me, I'd be happy to elaborate on this.
Glenn Ashmore
One last question: How do you determine the pump capacity to throw a 1"
thick stream various distances?
The idea is to have several pump/nozzle units aranged in pairs appear
to randomly pass a slug of water back and forth. There would be a
central high pressure pump to supply the control stream. As the units
will be at different levels, I figure the lowest one would be equipped
with a second pump to redistribute the water. The other sumps would
have float valves to draw water as needed.
BTW, I am only acting in an advisory capacity on this project and will
probably just program a microcontroller to do the timing.
frank
at Bellagio (Las Vegas) are done.
The key is to have a very large air tank at moderatly high pressure.
Fill a known length of pipe with water, then open one end to the
high-volume, high-pressure air. The air exerts almost a constant
force as it displaces the water down the pipe (and presumably
though the laminar flow nozzle).
For a first approximation you use pure Newtonian physics of
solid objects. F=ma. Since you know gravity, the distance
and height to move the water, the density of water and can
consider the force (air pressure) to be a constant, the calculations
are easy.
Complexity is shifted to plumbing, air supply and microcontroller.
"Glenn Ashmore" <ru...@bellsouth.net> wrote in message
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