[Robotgroup] water flow
Don Colbath
dcolbath at austin.rr.com
Sun Aug 13 08:47:18 PDT 2006
Water soluble plastic? Sounds interesting. What are it's uses? Do
you pour it into a mold and let it dry out?
Don
Richard Abbott wrote:
>If anyone is so inclined, I can get Polyethylene oxide at my work. Mike is right. At work they use it as a water soluable plastic.
> Rick
>
>Def Egge <robodigest at innervate.com> wrote:
> Of course, oil and water do not mix so well but, perhaps, that is all right.
>
>Polyethylene oxide dissolved in low concentrations can drastically alter
>the viscosity of water. Glycerine, methyl cellulose, sugars, low molecular
>weight alcohols, etc. are cheap, easily-obtained water-soluble substances
>that might be worth experimenting with.
>
>Fluorescein, mentioned in an earlier post, though fairly non-tocix, is a
>major irritant to skin, eyes, and mucus membranes. It might be wise to
>avoid triggering allergic / asthmatic reactions among onlookers. [I seem
>to remember that the fluorescein-containing lasers created respiratory
>problems when they leaked in a lab I used to hang out in.]
>
>All the best....
>
>
>Mike
>
>
>
>At 14:58 2006/08/10 -0500, you wrote:
>
>
>>If we are talking about making water look pretty, perhaps you could add
>>some other fluid to the water to change its properties (viscosity or
>>whatever). Oil comes to mind as a possibility.
>>
>>
>>
>>Leslie Filip wrote:
>>
>>
>>>Did you use angled blades that were in sync with the speed of flow?
>>>If this is not taken into account then the result sucks. FYI I am
>>>talking about blobs that are around a half inch in diameter, not
>>>sprinkle. I think a frozen arc of blobs is magnitudes more
>>>interesting than a single vertical stack of droplets, granted even
>>>those are pretty cool looking with the fluorescent dye and UV LEDs.
>>>
>>>I keep saying this so please if someone has seen otherwise correct
>>>me: "The start of laminar flow requires a ramp-up of speed within the
>>>output chamber before exit." This is why trying to pulse blobs with a
>>>plain valve does not work. It is the uniform speed and trajectory of
>>>water molecules in laminar flow as well as surface tension that
>>>allows the blobs to remain coherent.
>>>
>>>Looking forward to the party.
>>>
>>>Les
>>>
>>>
>>>On 10 Aug 2006, at 12:47 PM, brooksdesign wrote:
>>>
>>>
>>>
>>>
>>>>I tried several chopping type methods but none worked as good a my
>>>>sprayer hose valve thing in the sink .I have been messing with
>>>>chamber with water feeding in the side ,a nozzle on top and a
>>>>diaphram on bottom that can be pulsed by mechanical piston on a
>>>>crankshaft of with air pressure .I discovered this while rinsing
>>>>out a soap bottle ,good blobbieness .I'm building this as part of
>>>>the stage show I'm planning for the .....wait for it ....The last
>>>>party and official house dissassembly event at brooks' place in
>>>>Bastrop (no date yet but soon).
>>>>-brooks
>>>>
>>>>-----Original Message-----
>>>>
>>>>
>>>>
>>>>>From: Leslie Filip
>>>>>Sent: Aug 10, 2006 7:29 AM
>>>>>To: Austin Robotgroup Mailing List
>>>>>Subject: Re: [Robotgroup] water flow
>>>>>
>>>>>If the blades are in a blower-type arrangement instead of a fan-like
>>>>>arrangement it would chop the water more smoothly. The nozzle would
>>>>>have to be shooting from within the cage though.
>>>>>
>>>>>Les
>>>>>
>>>>>
>>>>>On 10 Aug 2006, at 2:53 AM, Leslie Filip wrote:
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>>Gray,
>>>>>>
>>>>>>I believe it is still laminar flow you are wanting, only that
>>>>>>instead
>>>>>>of constant streams you want blobs. In order to accomplish this the
>>>>>>material has to have a ramp up of speed inside the laminar flow tube
>>>>>>before it exits. In the examples I have seen, it was not possible to
>>>>>>have a series of closely spaced blobs using only control valves.
>>>>>>There may be a solution.
>>>>>>
>>>>>>If you have an arc of laminar flow water, I believe you could
>>>>>>mechanically chop it into blobs, removing the water where you want
>>>>>>space. Think of the way a jet engine's blades are tilted. As the
>>>>>>water passed through rotating blades the entry point and exit point
>>>>>>of the blades in the water column would coincide with the forward
>>>>>>motion of the water arc, thus chopping it into a series of small
>>>>>>cylinders. Then through surface tension, each cylinder would reshape
>>>>>>itself into blobs. It is the lack of uncontrolled angular momentum
>>>>>>that allows the blob to remain a blob.
>>>>>>
>>>>>>There is a limit to the speed at which the water can travel as a
>>>>>>blob, however. When the speed goes beyond a certain point, the air
>>>>>>pressure at the front of the blob destabilizes it. In a parabolic
>>>>>>arc, this is as true for the speed at which the water exits the
>>>>>>nozzle as it is for the descent.
>>>>>>
>>>>>>The arcs I saw in Las Vegas in some of the smaller water gardens
>>>>>>went
>>>>>>about 10-12 feet without a problem. The arcs are more prone to
>>>>>>destabilization than blobs due to surface tension and the differing
>>>>>>speed from one part of the column to another. I don't think there
>>>>>>would be any problem at all with blobs remaining blobs over this
>>>>>>distance.
>>>>>>
>>>>>>Les
>>>>>>
>>>>>>
>>>>>>On 09 Aug 2006, at 5:26 PM, Gray Mack wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>>What I am looking for is a term for creating liquid
>>>>>>>blobs. How big they can be and stuff based on driping
>>>>>>>from a drop tower or launched.
>>>>>>>
>>>>>>>Another approach- Put some LED's, a microcontroller, a
>>>>>>>capacitor, and an inductor+rectifier into a bunch of
>>>>>>>ping pong balls. Fire them from an air blower/cannon
>>>>>>>at synchronized intervals in an arch or straight down
>>>>>>>or through a clear pipe and when they land they roll
>>>>>>>to a hopper to be recycled. As they are loaded into
>>>>>>>the cannon the capacitor is charged through the
>>>>>>>inductor via a varying magnetic field at the cannon
>>>>>>>and instructions on when to light up are also sent
>>>>>>>through the field to each ball. The capacitor has
>>>>>>>enough power to blink LEDs a few times during its
>>>>>>>travel as directed by the cannon.
>>>>>>>-Gray
>>>>>>>
>>>>>>>--- Shane Geiger wrote:
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>>FYI: http://en.wikipedia.org/wiki/Laminar_flow
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>Paul Atkinson wrote:
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>Gray,
>>>>>>>>>
>>>>>>>>>I don't think you'll have a problem if you
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>aren't susceptible to jitter between pulses (as
>>>>>>>>stepper motors are.)
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>You may have to have a special driver (giveio)
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
>>>>>>>>or something like that to access the parallel port
>>>>>>>>under Win XP/NT/2k if memory serves.
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>>The opposite of laminar flow is turbulent flow.
>>>>>>>>>
>>>>>>>>>Paul
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>
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>>>>>>>
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>>>>>>
>>>>>>
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>>>>>
>>>>>
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>>>
>>--
>>Shane Geiger
>>IT Director
>>National Council on Economic Education
>>sgeiger at ncee.net | 402-438-8958 | http://www.ncee.net
>>
>>Leading the Campaign for Economic and Financial Literacy
>>
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>>
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